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WIWill)”“WNW/HUI!)ll'J”MINIMUM!HUM 310 764 8043 f /\/07€~'LAST NAME /5 VAC/V'MRL/NDF MSU LIBRARIES RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES wiII be charged if book is returned after the date stamped beIow. MA '04 WGIG6 1 DEC 1 6 1998 N {11.51 10;}? 1 AFRO a 2008 @égloa "DOWNFALL": THE AMERICAN PLANS FOR THE INVASION OF JAPAN IN WORLD WAR II BY Dean M. Vander Linde A THESIS Submitted to Michigan State University in partial fulfillment of the requirements ‘ for the degree of MASTER OF ARTS Department of History 1987 ABSTRACT "DOWNFALL": THE AMERICAN PLANS FOR THE INVASION or JAPAN IN WORLD WAR II by Dean M. Vander Linde The dropping of the atomic bombs on Hiroshima and Nagasaki in August 1945 brought about a surrender by Japan and an end to World War II. At the time the Americans were preparing to launch a massive invasion of Japan, scheduled to begin on 1 November 1945 with an assault on the southern- most of the Japanese home islands, Kyushu. This thesis, making extensive use of primary sources, examines the evolution of American strategic views regarding an invasion as well as detailed descriptions of the various operational plans. Maps are included to help acquaint the reader with Japanese geography and to better understand the various tactical plans. Copyright by DEAN MARVIN VANDER LINDE 1987 ACKNOWLEDGMENTS While the production of a substantial work such as a thesis is for the most part an individual achievement, other people play key roles in the endeavor. I would like to express my profound gratitude to some of them. My thesis diretor, Dr. John W. Coogan, played a decisive role by suggesting the topic to me at a time when I was unsure of what direction my graduate studies should follow.: His lucid comments and insights were valuable in honing the final product. Special thanks also go to Dr. Donald N. Lammers, who took time out of his busy schedule as Director of the Honors College to be my second reader. I studied under Dr. Lammers earlier in my academic career and learned a great deal from the experience. I consider it a privilege to have had the . opportunity to work with such distinguised scholars as Dr. Lammers and Dr. Coogan. Last, but by no means least, special thanks go to my parents. Their support and encouragement was especially ‘valuable when the light at the end of the tunnel seemed so dinnand distant. Without them, I doubt if I could have accomplished this . ii TABLE OF CONTENTS List Of MapSOOOOOCI.00.0.0...000......OOOOOOOOOOOOOOOOOOOOiv List Of AbbreViationSOOOIOOOOOOOOOOOOOOOOCOOOOOOOOOOOOOOO00v IntrOductionooocooo.onoooooooooooooooooooooooooooooooooooool Chapter 1. Chapter 2. Chapter 3. Chapter 4. Chapter 5. Chapter 6. Chapter 7. Chapter 8. Chapter 9. Chapter 10. Chapter 11. Chapter 12. Early Thoughts About an Invasion..............4 Selecting a Target...........................17 Kyushu.......................................30 Strategic Issues.............................41 Command Reorganization.......................53 The Decision to Invade.......................64 OLYMPIC......................................79 Northern Honshu.............................102 CORONET.....................................lll Northwestern Kyushu.........................126 Operations Following CORONET................136 Summary and Conclusions.....................154 NoteSOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO0.0.00.0..158 Bibliography....... ..... ......... ...... ..................170 iii LIST OF MAPS Map l. Orientation Map of Japan...........................3 Map 2. Plan for the Invasion of Southern Kyushu (JPWC 235/3)..... ..... ......... ........ ...39 Map 3. Plan for the Invasion of Southern Kyushu (Operation "OLYMPIC").....................86 Map 4. Japanese Troop Dispositions, August 1945... ..... ..94 Map 5. Plan for the Invasion of Northern Honshu (JWPC 398/1).............................109 Map 6. Possible Invasion Routes, Kanto (TOKYO) Plain (JWPC 263/4)o.cocoooooooooooooooooooolls Map 7. Plan for the Invasion of the Kanto (Tokyo) Plain (JWPC 263/4).....................ll9 Map 8. Operations Preceding CORONET (JWPC 359/1)........123 Map 9. Plan for the Invasion of Northwestern Kyushu (JWPC 363/1). ......... ...............134 Map 10. Estimated Japanese Troop Dispositions, Post-CORONET (JWPC 333/1)..................137 Map 11. Plan for the Invasion of the Shimonoseki Strait Area (JWPC 333/1).................14l Map 12. Plan for the Invasion of the Nagoya Plain (JWPC 333/1)............................l44 Map 13. Orientation Map, Osaka-Kobe—Kyoto Area..........l46 Map 14. Plan for the Invasion of ‘the Hakodate-Aomori-Ominato Area (JWPC 333/1) ....... .....I49 Map 15. Plan for the Invasion of 'the Sapporo Plain (JWPC 333/1). ....... . ...... ....... ..... 152 iv LIST OF ABBREVIATIONS CINCAFPAC.......Commander-in-Chief, U.S. Army Forces Pacific CINCPAC...............Commander-in-Chief, U.S. Pacific Fleet CINCPOA..............Commander-in-Chief, Pacific Ocean Areas CINCSWPA. O O CCS...‘ CPS...’ FEAF. O O JCSOOOOO JICOOOO JPS.... JSSC... JWPC . O 0 MAC.... MAWOOOO RCTOOOO USASTAF.... .......Commander-in-Chief, Southwest Pacific Area ...........Combined Chiefs of Staff ............Combined Staff Planners ..............Far Eastern Air Force ..............Joint Chiefs of Staff .......Joint Intelligence Committee ...............Joint Staff Planners ...Joint Strategic Survey Committee ..........Joint War Plans Committee ............Marine Amphibious Corps ....................Marine Air Wing .............Regimental Combat Team ......U.S. Army Strategic Air Force INTRODUCTION The dropping of the atomic bombs on Hiroshima and Nagasaki in August 1945 brought about an unconditional surrender by the Japanese empire and the end of World War II. At that time the United States was preparing to launch a massive invasion of Japan, scheduled to begin on 1 November 1945. While the atomic bombs killed and maimed hundreds of thousands of people, they prevented the loss of far. more' lives, both American and Japanese, that an invasion would have entailed. No historian has written a comprehensive work on DOWNFALL, as the invasion was code-named. A number of works, such as the British and U.S. Marine Corps official histories of the war against Japan, written during the 1960's, examined the plans for Operation OLYMPIC, the first phase of the invasion, an assault against southern Kyushu on 1 November 1945. They also made passing reference to Operation CORONET, the planned‘ invasion of the Tokyo Plain, tentatively scheduled for March 1946. There was a great deal more material on the invasion plans, but most of these documents Ivere unavailable due to security classifications. Although Inaterial concerning the invasion plans was declassified and [made available to the scholarly community by 1974, it has not been exploited effectively. This study attempts to explain how the Allies reached the decision to invade Japan, and the tactical plans for the assault. One of its central features is its emphasis on the decision-making process by which the planners chose and rejected various courses of action. The research is based for the most part on American Joint Chiefs of Staff documents. Secondary sources are used where possible, mostly to provide the reader with background concerning early strategic planning for the war against Japan. Maps are furnished to help acquaint the reader with the geography of. Japan and to better understand the various tactical plans. _MAPS 5 8114’ MAP 13 \HONSHU O MAPS 9&11 " MAPS 6&7 HIROSHIMA SHIKOKU MAP 12 MAP 1. ORIENTATION MAP OF JAPAN CHAPTER 1 EARLY THOUGHTS ABOUT AN INVASION The first mention of a possible invasion of Japan by the Allies occurred in May 1942. The American Joint War Plans Committee (JWPC) drafted a comprehensive strategic plan for the defeat of Japan, JWPC 15. The JWPC admitted that "The unconditional surrender of JAPAN may require the invasion of the Japanese homeland." The planners did not consider such an invasion inevitable, however. Control of the sea, together with an intensive bombing offensive against Japan, might bring about an unconditional surrender without resorting to an invasion.1 JWPC 15 outlined a six-phase plan by which the Allies“ could obtain bases in eastern China from which to interdict the sea lines of communication (SLOCs) between Japan and the occupied territories of southeast Asia and to bomb the Japanese homeland itself. In phase one the Chinese, assisted by the United States, would expand their campaign against Japanese forces in China. .The British, with Chinese and American assistance, would recapture Burma in order to ensure a secure overland supply route to China. American forces would advance westward across the central Pacific to Open a line of communication to the Celebes Sea. In phase two, the British would open the Straits of Malacca and force dispersion of Japanese forces in the area. The United States Ivould recapture the Philippines, and the Chinese would make [preparations for the seizure of Hong Kong. In phase three the British would expand their operations in southeast Asia, while the United States would gain control of the northern portion of the South China Sea and assist the Chinese in seizing Hong Kong. In phase four, the Chinese, assisted by the Americans and British, would establish bases in eastern China from which to launch a large-scale bombing campaign against Japan. The campaign would be carried out in phase five, with the United States conducting the bulk of it. Phase six was the invasion of Japan itself. Should it prove to be necessary, the United States would assume the major share.2 JWPC 15 was presented to the British Chiefs of Staff at” the TRIDENT conference in Washington in May 1943. The British were not happy with the role the plan outlined for them. They did not share American faith in China's contribution to the war, and believed that a Burma campaign would accomplish little except to divert vital resources from the war in Europe. The British preferred a campaign against Malaya and the Netherlands East Indies, in order to threaten Japan's access to the region's raw materials, as well as to regain the ”face" they had lost with the fall of Singapore. But the United States Joint Chiefs of Staff (JCS) were firm on China and the necessity of a Burma campaign. Since there was no consensus on strategy, the Allies agreed at TRIDENT to send an American planning team to London to meet with its counterparts to resolve the differences. The American team arrived in London in June, and the JCS were anxious to get a British commitment for a Burma campaign. In the meantime, in Washington, American planners, based on a recommendation by the JWPC, proceeded with their own "studies on the defeat of JAPAN, with a View to RETAINING the INITIATIVE and LEADERSHIP now established in relation to the British." They did not want any British interference in developing Pacific strategy.‘3 In discussions in London in June and Washington in July the planners drafted a comprehensive strategic plan for the war against Japan and submitted it to the Combined Staff Planners (CPS). The plan, CPS 83, was quite similar to JWPC 15, though it went further in that it listed specific objectives and provided a timetable for their seizure. Thet timetable was very conservative, not forseeing the strategic bombing of Japan to begin until 1947, with any invasion taking place in late 1947 or, more likely, sometime in 1948. The plan was drawn up by committees representing different interests and ideas, and reflected it in many ways. On the issue of Burma, the planners were unable to reach a consensus, so the plan contained both the American and British concepts of operations. Any differences were left to be resolved by the Combined Chiefs of Staff (CCS)! CPS 83~examined a wide variety of topics, including the possibility of an invasion of Japan. In JWPC 46/5, a working paper used in drafting the final plan, the planners stated that "in order to insure the defeat of the Japanese we must be prepared to invade Japan and to destroy the armed forces defending the homeland." It was also imperative to defeat Japan as soon as possible after the end of the war in Europe, for "potent economic reasons." The longer the war lasted, the longer the Japanese would be able to exploit their conquests and build up their military strength, while the the Allies would begin to feel dire effects from the prolonged existence of a war economy} JWPC 46/5 considered the Tokyo-Yokohama area as the main objective for any invasion, since it was Japan's largest industrial concentration as well as the center of government. A direct assault against Honshu was considered, but since it contained the largest concentration of enemy forces,. which. could be shifted rapidly to counter any landing, the authors" determined that the best course would be to seize one or more of the other islands first. Kyushu in the south and Hokkaido in the north appeared to offer the greatest potential for providing bases to support the main landing and to interdict the flow of reinforcements and supplies from the mainland. Kyushu would give Allied forces control of the Yellow Sea and the waters around Korea, though that might be accomplished from bases in eastern China and the islands south of Japan. Hokkaido was closer to the main landing areas on Honshu and, being somewhat more isolated from Honshu than Kyushu, might be easier to occupy as‘a limited objective, or as a diversion if the main drive came from the south.6 JWPC 46/5 also examined the need for bases from which to launch an invasion. The Soviet Maritime Provinces or Korea seemed like ideal locations, as they had harbors for staging a shore-to-shore assault and airfields from which to obtain tactical air support. However, the uncertainty of Soviet intervention in the war ruled out their territory. An invasion of Korea would have required a force nearly as large as that slated for Japan, and might also require Soviet assistance. Because of these factors, a ship-to-shore assault, with carrier-based air support, was seen as the only viable course of action.7 Shanghai, with its extensive port facilities, was also a potential target. It could serve as an air and naval base from which to bomb Japan and attack enemy LOCs. Because it‘ was vital to the Japanese, Shanghai would certainly be well“ defended and require a large force to capture it. JWPC 46/5 recommended that plans for the invasion of Japan be prepared with and without the capture of Shanghai as a preliminary operation. Some of its functions could be carried out from positions in the Ryukyus, Bonins, and Kuriles.8 The planners believed that staging bases for the invasion forces should be no more than 2,000 miles from Japan, in order to limit the amount of time the troops were confined aboard ship and to reduce the need to replenish the supporting naval forces near the assault area. Among the .POSSible bases were the Aleutians—Alaska area, the Carolines and Marshalls, the southern Philippines and Borneo, and Indochina and Singapore. Prior to any invasion, the Allies ‘JOUId have to reduce Japanese air and naval strength, :industrial bases, and the morale of the people through attacks on the homeland, the sources of raw materials, and the reduction of shipping.9 The CPS reviewed CPS 83 before it was submitted to the CCS, and found fault with it in many areas. They considered the timetable of operations, even with possible rescheduling of operations, "so prolonged as to be unacceptable to the UNITED NATIONS," and further stated that "operations which do not contemplate the complete nullification of Japanese gains before 1947 will produce the serious hazard that the war against JAPAN will not, in fact, be won by the United Nations." This judgment was based on the economic factors. outlined in JWPC 46/5, and on the tenuous nature of publicfi opinion. Rear Admiral Charles M. Cooke, head of the U.S. Navy's War Plans Division, believed that it would be impossible to maintain popular support for the war into 1948, the most likely date for an invasion under the CPS 83 timetable. The Americans, therefore, proposed to defeat Japan within twelve months after the defeat of Germany. To accomplish this, forces would have to be transferred from Europe to the Pacific, a lengthy process. The Americans believed that the tranfers should begin from four to six months befdre the prospective defeat of Germany. The British, while agreeing that Japan must be defeated as soon as possible, refused to accept the American target date or any large-scale transfer of British forces before the defeat of Germany .10 The Americans and British disagreed on a number of other lO strategic issues. On Burma, neither side would change its position. Cooke opposed bypassing Burma in favor of a campaign against Singapore, believing that the latter campaign might require a large American commitment to aid the British, with a corresponding adverse effect on operations in the Pacific. The planners also differed on the importance of operations in the Solomons and New Guinea. The Americans believed that those operations played an important role in overall strategy by forcing a large commitment of Japanese forces for their defense. The British considered those campaigns a waste of resources for meager gain, and stated? that those resources would be better employed in the central“ Pacific.‘1 At the QUADRANT conference in Quebec in August 1943, the CCS rejected the strategy outlined in CPS 83. They did, however, approve a number of specific operations. In the central Pacific, the Gilberts, Marshall, Carolines, Palaus, and Marianas would be seized. In the southwest Pacific, Rabaul would be bypassed and northwestern New Guinea seized, while the British would open the Burma Road. Since there was no agreement on a specific overall strategy, the CCS directed the combined planning staffs to work on the problem. With the goal of defeating Japan within twelve months after the defeat of Germany, the American and British [planners drafted a new strategic plan, CPS 86/2. They cfloncluded that it would be necessary to invade the Japanese Inomeland in order to bring about Japan's unconditional ll surrender, but that an invasion was highly unlikely before the fall of 1945. Prior to any invasion, an intensive bombing campaign against Japanese industry would have to be carried out, as well as operations to destroy the Japanese navy, air forces, and merchant marine, and the seizure of the objectives decided upon at QUADRANT.‘2 In selecting follow-on objectives after the conclusion of the QUADRANT program, the planners considered four possible courses of action: an invasion of Hokkaido in the summer of 1945, or as an alternative, the invasion of FormoSa in the spring of 1945; an invasion of Formosa in the spring_ of 1945, with an assault on northern Sumatra in the spring or” fall of 1945 as an alternative; the seizure of Singapore before the end of 1945, with an attack on Formosa during the winter of 1945-46; and the execution of major diversionary operations in southeast Asia in the fall of 1944 or spring of 1945, with an invasion of Formosa during the winter of 1945-46. In conjunction with these operations, the British would expand their campaign in Burma, General Douglas MacArthur's forces would advance from New Guinea towards the Philippines, and Japan would be bombed from bases in central China. Aftér 1944, the Royal Navy would also make a large contribution in both the Pacific and Indian oceans.13 The planners considered the second of the four courses of action the "most promising way of finishing the war comparitively soon" with the least risk. They scheduled an invasion of Formosa for spring 1945 (with Luzon as an 12 alternate target), Hokkaido in the summer of 1946, and Honshu in the fall of 1946. In conjunction with these operations, the Kuriles might also be seized, either as a diversion or with cooperation from the Soviets.‘4 Nearly all of the officials who reviewed CPS 86/2 found fault with it. The Joint Staff Planners (JPS), for example, urged that Hokkaido be invaded in the late spring or summer of 1945, with the invasion of Honshu to take place no later than spring 1946. The British were uncertain when they could send a powerful fleet out to the Pacific, because most of their ships needed extensive overhauls after years of hard combat service. In the end, the CPS deferred any action on‘ cps 236/2.” Meanwhile, the JWPC worked on a modified version of CPS 86/2, the principal change being a revision of the schedule for the invasion of Japan to coincide more closely with the recommendations by the JPS. This new plan also did not meet with much approval. Vice Admiral Russell Willson, the Navy member on the Joint Strategic Survey Committee (JSSC), expressed doubts that it would be necessary to invade Japan in order to bring about an unconditional surrender. He rmaintained that the combination of air and sea blockade with 'the destruction of the Japanese navy and industrial base MKNlld be sufficient)6 Willson's view of the necessity of an .anasion was shared by many other naval officers, especially Admiral Ernest J. King, Chief of Naval Operations and Cknmnander-in—Chief, U.S. Fleet-(COMINCH) and Admiral William 13 D. Leahy, Chief of Staff to President Franklin D. Roosevelt. In their memoirs both King and Leahy wrote they they believed that Japan could be defeated without an invasion.‘7 During their service on the JCS, however, they expressed their views on the subject but were not inflexible. All decisions by the JCS required a unanimous vote, and Army Chief of Staff General George C. Marshall seemed convinced of the need for an invasion. Additionally, military prudence made it necessary to consider every possible course of action. The new plan was not well-received by the JCS. King was amazed by the choice of Hokkaido, and was puzzled how the~ planners proposed to reach it. They explained that Hokkaido“ would be approached from the central Pacific. King then asked why Hokkaido was chosen over Kyushu, since Kyushu was a logical extension of the planned central Pacific offensive. The planners replied that Kyushu had been considered and rejected because it would be more heavily defended than Hokkaido, and that there might not be enough landing craft for a sufficiently large assault force. In spite of these explanations, King remained unconvinced of the plan's value.‘8 Leahy was equally skeptical of the timetable for the invasion, believing that it was overly optimistic to think that the Japanese homeland could be conquered in less than a year; Neither Marshall nor General Henry H. Arnold, head of the Amnw'Air Forces, had any greater enthusiasm for the plan. The JCS sent it back to the planners for more work.19 Thus, after nearly a year, the Allies were still without 14 an overall strategic plan for defeating Japan. They would have one, however, after the SEXTANT (Cairo) and EUREKA (Teheran) conferences in November and December 1943. SEXTANT, where Roosevelt and British Prime Minister Winston Churchill met with Chiang Kai-shek, made obvious just how futile American efforts were to get the British and Chinese to assume a more active role in the war against Japan. Chiang agreed to send Chinese troops into northern Burma in an effort to reopen the Burma Road, with the stipulation that the British launch an offensive further south to engage Japanese attention. The British were not keen on the idea of‘ a Burma campaign, but did reluctantly accept an American proposal for an amphibious landing in the Andaman Islands, code-named BUCCANEER. Churchill did not like the idea of BUCCANEER, for he feared that it would divert resources from Europe, especially from some of his pet schemes for the Mediterranean, but he relented under American pressure}to Chiang returned to Chungking, while Roosevelt and Churchill went on to Teheran to meet with Stalin. At Teheran, the Americans got something they had wanted since Pearl Harbor, a Soviet commitment to enter the war against Japan after the defeat of Germany. This gave Churchill an excuse to cancel BUCCANEER, because it meant that China would not play a significant role in defeating Japan, and thus, the rationale for a major Burma campaign was no longer relevant.21 Perhaps more decisive than these factors was the outcome (of a battle that ended on the first day of the SEXTANT 15 conference. On 15 November 1943 American forces attacked Tarawa in the Gilberts and, after a fierce battle, seized the atoll. This campaign demonstrated the capabilities of naval carrier airpower and Marine Corps amphibious forces. Tarawa established the pattern for the drive through the central Pacific.22 The CPS drafted a new plan for defeating Japan, CCS 417. Its overall objective was "To obtain objectives from which we can conduct intensive air bombardment and establish a sea and air blockade against Japan, and from which to invade Japan proper if this should prove to be necessary." The CPS, proposed that the main effort be in the Pacific, along two' axes, through the central Pacific and through New Guinea, the Netherlands East Indies, and the Philippines. The two drives would be mutually supporting, and forces could be shifted between them as conditions warranted. This strategy would force the Japanese to disperse their forces to meet possible avenues of advance. If there were any conflicts in timing or allocation of resources, the central Pacific would get the nod, since it offered the prospect of "a more rapid advance toward Japan and her vital lines of communication; ~the earlier acqfiisition of strategic air bases close to the .Japanese homeland; and, of greatest importance, are more likely to precipitate a decisive engagement with the Japanese fleet.”23 The plans stated that operations in the North and South ‘Pacific, southeast Asia, and China would be in support of the 16 main operations in the Pacific, reflecting the downgrading of American hopes for significant action in China and Burma in the near future. The North Pacific, however, might assume greater importance when the Soviet Union entered the war against Japan. Since the occupation of Kiska in August 1943, the Army and Navy commanders in the Aleutians had pushed for an increased role for their theater, possibly even as the place from which to launch an invasion of Japan, but the climate, lack of adequate bases, and distance from the main Allied lines of communication made a large-scale commitment in the North Pacific impractical.2‘ The CCS were generally pleased with CCS 417, because a“ consensus had finally been achieved. Others were not as happy. MacArthur, in a display of his enormous ego, believed his theater should be awarded priority over the central Pacific, since it offered the shortest route t the Philippines. He sent his chief of staff, Major General Richard H. Sutherland, to Cairo to lobby for his cause, though he had no effect on the JCS.25 The JSSC, on the other hand, recommended that the central Pacific be given unqualified primacy over all other theaters, including the Southwest Pdcific, their reasons being the same as in CCS 417. Like Sutherland, the JSSC was also unsuccessful in xvinning the JCS over to its position. CHAPTER 2 SELECTING A TARGET During the next six months the Americans made considerable progress in the Pacific. In the Central Pacific, the Marshalls were captured in February, and Saipan, the first of the Marianas, was invaded on 15 June 1944. In the Southwest Pacific MacArthur's forces continued to leapfrog along the northern coast of New Guinea, seizing Hollandia and a number of other key positions. Future plans included the capture of the Palaus in September 1944, Mindanao in November 1944, and either Formosa or Luzon in February 1945.1 With American forces moving closer to~ Japan, it was necessary to devise a strategy that would bring. about the ultimate surrender of Japan, which meant that consideration would have to be given to an invasion. The JCS ordered the JPS to study the matter. Their report, JCS 924, is one of the most important yet least-known documents of the Pacific war.2 The JPS maintained that, with the seizure of Formosa, the objective set forth in CCS 417 would have been met. Aircraft based in Formosa, China, and the Marianas could attack the Japanese homeland and, together with the Navy, sever Japan's access to the vital raw materials of Southeast Asia and greatly reduce the flow of raw materials from Manchuria and Korea. As a result, the JPS recommended a new overall objective, "To force the unconditional surrender of Japan by (1) Lowering Japanese ability and will to resist by 17 l8 establishing sea and air blockade, conducting intensive air bombardment, and destroying Japanese air and naval strength, (2) Invading and seizing objectives in the industrial heart of Japan."3 This represented a major change in strategy. Invasion had been seen as a possibility, not a necessity. The vagueness of overall strategic planning, together with the fact that the Allies were far from Japan, had made any mention of an invasion abstract. As the Allies closed in on Japan, however, the matter of an invasion grew in importance, since it determined the choice of targets for future assaults. The JPS outlined the reasons behind their recommendation for an invasion. In their opinions, while the bombing and blockade of Japan would have a considerable effect on Japanese morale and ability to wage war, to believe that such actions could, by themselves, force an unconditional surrender was "overly optimistic." Even if the bombing and blockade, together with the destruction of Japan's naval and air forces, were effective, they would, in the opinion of the JPS, "involve an unacceptable delay in forcing an unconditional surrender."‘ Bombing and blockade might not bring about an unconditional surrender quickly, because they would not have much effect on the Japanese Army as a "force in being." As long as the army existed, the Japanese could -resj;3t and prolong the war. Air and naval power could <3Ontaribute to the reduction of Japan's military capability, 19 but they could not destroy the Japanese Army. Only another army could do that, and that meant an invasion. Secondly, economic and political factors made an invasion seem the best course of action. The economic concerns were examined in JWPC 46/5. The longer the war continued, the more the Japanese would be able to consolidate their positions, while the continuation of the war would strain on the Allied economies. This view was based on Cooke's concern over just how long public support for the war could be sustained. Bombing and blockade, while less costly than an invasion, would also take considerably longer to, force an unconditional surrender. Both the public and' Congress might question a strategy that prolonged the war, especially when the resources were available to end it relatively quickly. There might be pressure on the Administration for a quick end to the war and an end to shortages and rationing. The JPS listed three criteria for an invasion strategy. First, the advance to the industrial heart of Japan should be made in the fewest number of steps possible. Second, assaults should be made in areas where local tactical superiority‘could be achieved and maintained. Third, only areas suitable for basing forces for an assault on the industrial heartland should be considered. Based on these <1riteria, the JPS rejected a direct invasion of Honshu from Formosa because they considered the achievement of local taetical superiority impossible. Shikoku was also rejected 20 for the same reason. The JPS described Shikoku as a "geographical cul-de-sac of limited physical value and difficult for ground operations." The JPS limited the list to four possible choices, termed "main objectives": (orea, Hokkaido, China, and Kyushu.5 Korea was of great strategic importance to Japan, since it formed part of a nearly continuous land route between 'Japan and the Asian mainland. Raw materials from Korea and Manchuria were shipped to Japan, and supplies were shipped from Japan to its Asiatic armies. An Allied occupation of Korea, together with control of the sea, would isolate Japan from its supply of raw materials and its forces on the continent. It would provide extensive bases for aircraft within 600 miles of Japan's main industrial regions, as well as bases for naval forces to attack Japanese shipping. Additionally, a successful assault on Korea would, in the opinion of the JPS, result in an immediate Soviet entry into the war against Japan, and might prevent a withdrawal by the Japanese government to the mainland to continue the war if the homeland became untenable. Among the disadvantages of a Korean campaign were that it would require preliminary operations- to reduce Japanese air and naval offensive capabilities, would confront the large Japanese mainland armies in a location difficult for the Allies to reinforce, would require commitment of large forces before it could be "fully used by the Allies amd restricted approaches to the landing beaches.6 21 Hokkaido also played an important role in the Japanese war effort. It was the base for a large fishing fleet, and a source of raw materials, especially coal. It was a key link between Japan and the Kuriles and Sakhalin, and controlled the sea routes between the Pacific and the Soviet Far East, an important factor if the Soviets entered the war. There were a number of advantages to an assault on Hokkaido. It would tighten the blockade of Japan by severing the lines of communication with its northern territories and by allowing Allied naval forces access to the Sea of Japan, making possible attacks on Japanese coastal shipping. It offered; airfield sites within fighter range of Tokyo and the rest of” northern Honshu. It would probably be less heavily defended than Honshu or Kyushu, and could deal Japanese morale a serious blow through the invasion and occupation of Japanese territory. There were also a number of disadvantages to an assault on Hokkaido. It would not isolate Japan from the Asian maifland. The airfields were beyond fighter range of many Japanese industrial areas, such as Nagoya and Osaka. The assault would have to be carried out without land-based air support. Hdkkaido did not have any good harbors for use as naval bases, and it was distant from the main Allied lines of communication.7 The JPS saw China primarily as a base from which to ‘Parry'out the bombing, blockade, and invasion of Japan. To <2per1 a line of communication from Formosa to Chinese forces 22 in the interior would have involved a huge commitment, which would have diverted resources from the Pacific. Additionally, it would have been quite a while before the Chinese could have made a significant contribution to the defeat of Japan. Chinese forces in the interior, therefore, would have to manage as best they could with whatever logistic support they received. In light of this strategy, three areas along the coast were considered for assault: Foochow-Wenchow, Shanghai, and the Shantung Peninsula.8 Under Japanese occupation, Foochow-Wenchow protected the southern flank of the Japanese position in the Yangtze\ valley, controlled the East China Sea and the entrance to the" Yellow Sea, and provided advance air defense for Shanghai. In Allied hands this area would provide airfields from which to bomb Japan and bases from which to interdict Japanese shipping from the Korea Strait southward. Because the area was primarily rural and lacked the infrastructure needed by a large military force, it would have required extensive development to become a useful base for invading Japan. In any case, a lodgment in this area offered no real advantages over Allied control of Formosa. For these reasons, any invasion of‘ the Foochow-Wenchow area would have been a secondary effort. Shanghai's value to the Japanese was primarily as a transportation center. It served as an export point for 'supplying raw materials from the Yangtze valley to Japanese industry, and as a port of entry for supplying Japanese 23 troops in south-central China. In Allied hands, Shanghai would be an excellent staging base for an invasion of Japan. It also would open routes to the interior of China, threaten the Japanese position in China, and help protect the western flank of the American advance in the Pacific. Because of this strategic importance, Shanghai would be heavily defended and require a considerable force to seize it. Shantung protected the lines of communication between Japan and the various ports on the Yellow Sea and served as a barrier to the sea approaches to northern China and Manchuria. Preliminary operations to gain control of the Yellow Sea would be necessary before an attack was attempted.“ Allied occupation of the area would disrupt Japanese lines of communication through the Yellow Sea and provide bases from which to bomb Japan. As a possible base for the invasion of Japan, Shantung offered no real advantages over Formosa, though it would be a fine base for conducting operations against northern China, Manchuria, and Korea. The greatest disadvantage of assaults against Shanghai and Shantung was the prospect of "a major, costly, and protracted land campaign against strong enemy forces." Such a campaign would delay the invasion of Japan and accomplish little of strategic value. The JPS considered a limited assault on the Foochow-Wenchow area to be the only viable OPtion. Such a campaign would threaten enemy positions in the Yangtze valley, provide bases for bombing Japan and .intxxrdicting Japanese lines of communication, indirectly 24 assist the Chinese forces in the interior by diverting Japanese troops, and act as a diversion by concealing 'Allied intentions from the Japanese. Among the disadvantages were the possibility of unexpectedly heavy Japanese resistance, the possible requirement for a large commitment of Allied troops to defend the area, and the limited potential of the region for airfield development.9 Kyushu occupied an extremely vital position in the Japanese war effort. It was essential to maintaining communications between Japan and the mainland. The loss of Kyushu would do much towards isolating Japan from the rest of Asia. The Fukuoka—Shimonseki region in northwestern Kyushu“ contained vital defense industries, and their loss would deal a serious blow to the Japanese war effort. Kyushu also controlled the southern entrance to the Sea of Japan, as well as two of the three entrances to the Inland Sea, enabling it to serve as a secure base for the Japanese fleet. Air bases on Kyushu provided the Japanese with an advance fighter defense against attacks from the south and west, as well as for conducting offensive air operations over the East China Sea. There were many advantages to an Allied occupation of Kyushu. It would completely isolate Japan from the rest of Asia, and would bring all of the industrial heart of Japan Within range of medium bombers and fighters. It would make .Sasebo and the Inland Sea useless as bases for the Imperial PLaVYR. It would also open a route from the Pacific to the 25 Soviet Far East. An assault on Kyushu would engage the enemy in an area difficult for him to reinforce, and would draw enemy reserve strength to the south, thereby weakening Japanese defensive capabilities and creating favorable tactical conditions for an eventual assault on Tokyo. An invasion of Kyushu could be supported by the bases and lines of communication established during the drive across the Central Pacific. Last, but by no means least, an occupation of Kyushu would deal a serious blow to Japanese morale. There were a number of disadvantages to an assault on Kyushu. It would confront the enemy in an area that he would_ exert a maximum effort to defend. Terrain difficulties would” hinder any Allied attempt to achieve control over the entire island. There were limits to the basing potential for aircraft. An assault would probably not have the advantage of surprise, and its success was dependent upon the reduction of Japanese capabilities for reinforcement}0 In order to carry out any of the previously mentioned campaigns, "intermediate objectives" would have to be seized. Three possible objectives were examined: the Kuriles, the Ryukyus, and the Bonins. Allied‘control of the Kuriles would assure control of the Sea of Okhotsk and a supply line to the Soviet Far East. The Kuriles would provide air and naval bases for an attack on Hokkaido and from which to destroy the enemy fishing fleet in northern waters, with a serious effect on the Japanese Ehconomy. An assault on the Kuriles would force the Japanese 26 to disperse their forces, and could serve as a diversion if the Allies chose to attack Japan from the south. Among the disadvantages of an assault on the Kuriles would be the commitment of substantial forces to the northern Pacific, causing a wasteful dispersal of resources, unless Hokkaido was chosen as a main objective. Because of the adverse climate, air operations would be less effective than in southern areas, which, together with enemy interior lines of communication, would reduce the amount of damage inflicted upon the Japanese."1 The Ryukyus were seen as a stepping stone from Formosa. to Kyushu. Long-range fighters based in the Ryukyus could‘ operate over Japan as far north as Osaka, and could provide air support for an assault on Kyushu. These same fighters could also escort bombers flying from Formosa and Foochow-Wenchow on missions over Japan. Due to limited port facilities and the existence of only four good anchorages in the entire chain, the Ryukyus had, in the opinion of the JPS, limited potential as a major fleet base. The Bonins were part of a string of small islands that led directly to Tokyo. Because of their strategic importance,‘any assault on the Bonins would undoubtably be met by an all-out effort by the Japanese fleet, making possible a decisive naval engagement to destroy the Imperial ‘Navy once and for all. Because of the island's rugged terrwain and lack of harbors, their basing potential for large forces was limited. They could serve, however, as an 27 adequate base for fighters to escort Marianas-based B-29's on missions over Japan. In choosing the main objective for supporting the eventual assault on Tokyo, the JPS quickly rejected China and Korea. Operations in either area would have meant a long, difficult, costly campaign against large enemy forces, with physical conditions and enemy dispositions making a lodgment in either area difficult if not impossible. That left Hokkaido and Kyushu as the only choices. In terms of blockade, air and naval bases, effect on the Japanese economy, and air, naval, and logistics support, Kyushu was, far superior to Hokkaido. The only advantages Hokkaido had. were probable lighter defenses and the element of surprise. The JPS, therefore, concluded that Kyushu was the best choice for a main objective.‘2 Based on this choice, the JPS recommended advances through the Bonins and Ryukyus and in southeast China to obtain bases for blockading and bombing Japan and to support an assault on Kyushu. The Kyushu operation would destroy major Japanese forces and obtain a position from which to support an~ invasion of Tokyo. The Bonins and Ryukyus operations were tentatively scheduled for 15 April and 1 May 1945, respectively. The assault on Kyushu was scheduled for 1 October 1945, and the assault on Honshu in the vicinity of Tokyo for 31 December 1945. The JPS believed that ten divisions would be required for the Kyushu operation, and ftunrteen for the invasion of the Tokyo area. The availability 28 of troops was contingent upon the rate of redeployment of troops from Europe after the defeat of Germany.‘3 The Joint Chiefs approved JCS 924 without much debate. The British Chiefs of Staff, however, had some doubt about the new objective. They did not receive a complete draft of the report, but only a recommendation that the overall objective be restated, together with the explanation that an invasion would avoid the "unacceptable delay" involved in trying to defeat Japan solely "by sustained aerial bombardment and the destruction of her sea and air forces." The British agreed to accept the new objective, but wanted assurances that the new objective would not affect the‘ priorities for the defeat of Germany, and that the change did not mean authorization for an extension of operations in the Pacific not already approved by the CCS. The British apparently believed that the Americans were attempting to circumvent established procedures and deny the British a voice in strategic planning)‘ The Americans assured the British that, with the commitment for the invasion of France, there was no reduction in the priorities for the defeat of Germany. As for the second item, the Americans responded that since the Pacific had been deSignated a United States-controlled area, the CCS had little say concerning it. They would be advised on operations so far as they affected the overall objective of an unconditional surrender of Japan, but approval of the CCS was not mandatory. The British accepted the new objective, 29 thus paving the way for an invasion of Japan.‘5 JCS 924 was significant in a number of ways. It outlined, with a great deal of accuracy, the operations that were carried out in the Pacific during 1945. More important, however, it brought the issue of an invasion into the limelight, thereby forcing the CCS to make a decision about it. With the decision, planning for the invasion could now begin in earnest. CHAPTER 3 KYUSHU Since the JPS considered Kyushu the best place from which to support an assault on the Tokyo Plain, the JWPC began work on an invasion plan, submitting it to the JPS on 4 September 1944. The plan, JWPC 235/3, outlined an invasion of southern Kyushu with a target date of 1 October 1945. This date chosen was in keeping with the schedule of operations outlined in JCS 924, offered the best prospects for favorable weather, and marked the beginning of the dry-paddy season on the island.‘ The invasion of southern Kyushu was the most ambitious‘ operation yet planned for the war against Japan, and in some' ways would have dwarfed the June 1944 invasion of. Normandy. Among the forces slated for the operation were thirteen divisions and eighty-six independent units of such troops as combat engineers, signal, artillery, and armor; 2,700 warships, ranging from aircraft carriers and battleships to LSTs and LCIs; and nearly 4,300 land-based and more than 2,900 carrier-based aircraft. In keeping with the overall strategic concept stated in JCS 924, the planners believed that an invasion of Kyushu would have to provide a secure lodgment, with basing facilities for air and naval forces to carry out air strikes against targets in the industrial heart of Japan and to tighten the naval blockade of the islands, support the invasion of the Tokyo Plain, and to fix, engage, and destroy major enemy forces.2 30 I} M 1.. (I) () (I) "(J 31 Kyushu is divided into two parts by the Sammyaku mountain range, which crosses the island from southwest to northeast. Northern Kyushu contains the main ports as well as the industrial and transportation centers, and its loss would seriously affect the Japanese war effort. There were, however, a number of disadvantages to making the initial landings in this area. The sea approaches were difficult and heavily defended, and there were few beaches suitable for large-scale landings and later deployment. The large population and heavy urbanization of the region would exacerbate the problem of dealing with a hostile population. Southern Kyushu, on the other hand, was more rural, with‘ more room for maneuver. The landing beaches were well-suited for the massive scale of the invasion. More importantly, though, landings in southern Kyushu would place a greater strain on the enemy's defensive capabilities than landings in the north, since the mountains and limited lines of communication between north and south would hamper Japanese attempts to transfer troops from the north in response to an assault. Southern Kyushu, therefore, was selected as the site for the initial assault.3 The geheral concept of the operation consisted of four phases. In the first, or Preparation, phase, covering the period 0-3 to D-l, aircraft would conduct strikes against enemy air and naval forces, communications, and industrial targets on Kyushu and Honshu. They also would carry out reconnaissance missions over the target area and, in SE C IINA 32 conjunction with submarines, lay minefields near major Japanese naval bases to bottle up the Imperial Navy. In the second, or Assault, phase, covering the period D-Day to D+14, the troops would go ashore, preceded by an intensive air and naval bombardment of the landing areas. The assault was designed to seize four major objectives. The most vital, the early seizure of which was considered essential to a secure lodgment, were the port of Kagoshima and the airfield complex near Kanoya. Of lesser significance were the important transportation centers of Kokubu and Miyakonojo, located at the heads of Kagoshima and Ariake I Bays,~ respectively. To achieve these objectives, landings would bef made at three sites on the western, southern, and eastern coasts of the island.4 The Western attack force, consisting of four divisions and considered the main force, would land south of Kushikino. This would give the assault force easy access to the landward approaches to Kagoshima, to the southern part of the Kagoshima Peninsula, and to the vital lines of communication to northern Kyushu. The troops would rapidly advance eastward and seize the port of Kagoshima. To counter a possible major enemy counterattack from the vicinity of Miyakonojo around D+10, the Americans would establish a temporary defensive line in the high ground across the peninsula just north of Kagoshima, between the towns of Kushikino and Wakimoto. One division of the Western force would land further south and, in conjunction with the 33 Southern force, would destroy enemy forces in the southern part of the peninsula and seize key military targets. The Southern force, consisting of a reinforced division, would land just east of Makurasaki, gain control of the entrance to Kagoshima Bay, and seize the nearby airfields. A motor torpedo boat base would be established and mobile coast artillery emplaced. As soon as possible, a line of communication would be established with the Eastern force on the oppoSite shore of the bay. Once these missions were accomplished, the Southern force would come under the control of the Western force for further operations. The three divisions of the Eastern force would land at; the head of Ariake Bay, with the primary mission of capturing the airfield complex near Kanoya. Once that mission was accomplished, the bulk of the force would advance northward to counter any enemy attempt to move troops from the northeast to the head of Kagoshima Bay. The remainder of the force would destroy enemy resistance along the shore of Kagoshima Bay and establish communications with the Western force across the bay. The third, or Consolidation, phase, would see the arrival of the first major reinforcements, with five more divisions landing on the island by D+15. While existing tactical conditions would necessarily ' determine the employment of these troops, the planners suggested one possible scenario. Two divisions would reinforce the Western force if it seemed that the main enemy effort would be in 34 that area, since communications were better. Another division might go with the Eastern force to assist in mopping up Japanese resistance along the shores of Kagoshima Bay and securing it for American use. The two remaining divisions might stage an amphibious landing on the east coast near Miyazaki and, in conjunction with an advance by the Eastern force on Miyakonojo, secure the eastern flank and seize control of the lines of communication in eastern Kyushu. Miyazaki was key to communications between southern and northern Kyushu, yet for various reasons it was not selected as a target for the initial landings. The area contained few; potential airfield sites and no ports or anchorages of any size. Terrain difficulties would hamper troops in attempting to fan out from the beachhead to seize other targets in southern Kyushu. Lastly, landings in this area would be too far removed by distance and terrain to be within safe supporting distance of the Western or ~Eastern forces. Miyazaki could be captured later, however, either by an overland advance or by an amphibious assault. If it did not prove to be a feasible target, due to enemy strength or weather, AbUratsu, further south, was as an alternate target, though it was not as advantageous. During Phase III operations, the Western and Eastern forces would link up at the head of Kagoshima Bay, with the commander of the Western Force then assuming tactical command of all ground forces on the island. The troops would seize the Yokogawa-Kokubu area at the head of Kagoshima Bay, 35 followed by the seizure of the key communication centers of Miyakonojo and Miyazaki in the east and the Sendai valley in the west. Eventually, a defensive line would be established, running across the island from Sendai in the west, through Yokogawa and Miyakonojo, to either Miyazaki or Aburatsu in the east. From this position American forces could continue to exert pressure on the remaining enemy forces on Kyushu with the threat of further offensive action to the northwest and northeast.5 In the fourth, or Exploitation, phase, the Americans would use their lodgment on Kyushu to tighten the blockade of; the other home islands and to increase air strikes againstf targets in the industrial heartland of Japan. Kagoshima Bay would be established as an advanced naval base, existing airfields would be put into operation, and other facilities would be built as required. The Air Force estimated that nine fighter groups, four groups of medium bombers, four groups of heavy bombers, four night fighter and three reconnaissance squadrons could be based on Kyushu by D+45. Further offensive action by ground forces against the vital industrial region of northern Kyushu was also contemplated. This would assist the assault on the Tokyo Plain by fixing, engaging, and destroying enemy forces that might otherwise be used in the defense of Tokyo. The use of airborne troops: to secure passes through the Sammyaku range would permit the eXploitation of tactical opportunities by attacking forces, for they would no longer be restricted to the narrow coastal 36 corridors that connected the two halves of the island. The employment of airborne troops, however, was contingent upon the troop requirements for the Tokyo Plain.6 The planners realized that the Japanese would make a maximum effort to prevent a successful landing on Kyushu, and went on to describe enemy capabilities and probable reactions. They estimated enemy air strength in all theaters at 3,000 combat aircraft, of which 1,900 were based in Japan proper, the Kuriles, and Sakhalin. To counter the landings, the Japanese would have some 500 aircraft based on Kyushu, augmented by 300 more aircraft based in southern Korea,l southwestern Honshu, and Skikoku.7 To reinforce these unitsf and replace losses, the Japanese could not transfer forces from other parts of Japan without seriously weakening defenses of other vital areas, such as Tokyo, Yokohama, Kobe, Osaka, and Nagoya. The only possible areas the enemy could draw reinforcements from without affecting the homeland were Manchuria, China, and Korea. Some 300 aircraft could be obtained from these areas, though if the Soviets attacked Manchuria at the same time as the invasion of Kyushu, those aircraft would probably not be available to counter the invasion. Air opposition would be heaviest during the first few days of the invasion, and then progressively weaken as losses mounted and reserves were reduced.8 At the time the plan was drafted the main Japanese fleet had not yet been engaged in a major, decisive battle. If the Japanese fleet had refused battle by the time of the 37 invasion, the planners estimated that its strength would consist of fifteen aircraft carriers, four modern and six old battleships, thirteen heavy and eleven light cruisers, eighty—three destroyers, and between sixty and eighty-nine submarines. If, on the other hand, the Imperial Navy had been met and defeated in a decisive engagement, its strength would have been reduced by some seventy to eighty percent. The handful of old battleships, cruisers, and destroyers might, with some air cover, offer some resistance to the landings, though given overwhelming American naval superiority, enemy naval opposition would be short-lived.§ The greatest threats the Japanese fleet posed against an' assault were attacks by submarines and light forces such as motor torpedo boats (MTBs) in the landing areas.9 With the looming threat of invasion, the Japanese would begin tranferring troops from the mainland to bolster their forces in the Home Islands. The planners estimated that by D-Day the Japanese would have fifteen infantry, fourteen depot, and two armored divisions, four independent mixed brigades, and four armored regiments stationed .in Japan proper. Of these, six divisions plus various other units, for a total‘of 125,000 men, would be on Kyushu. Three divisions and two armored regiments would be located in northern Kyushu, while the remaining three divisions would be deployed in the southern part of the island. One division would probably defend the eastern coastal plain between Miyazaki and Kanoya, another would cover the western Coastal 38 plain between Sendai and Makurasaki, and the third would be stationed near the head of Kagoshima Bay, from where it could move to reinforce either of the other divisions. In addition, garrison troops and fixed defenses would protect Kagoshima Bay.‘o With only three divisions plus garrison troops to oppose the landings, the assault forces would probably have had little difficulty in establishing a lodgment on Kyushu. Reinforcements would move in from other areas in an attempt to contain any American advance. There were two depot divisions on Kyushu, each capable of supporting four combat] divisions. Taking advantage of internal lines of' communication, four more divisions could be supplied from Honshu. Because of terrain difficulties, however, the planners believed that the Japanese could support only ten divisions in sustained combat. Reinforcements would begin to arrive from staging areas near Kobe-Osaka and the Tokyo Plain on D+2, with a division arriving daily until the maximum number was reached. As long the lines of communication remained open, the Japanese would endeavor to maintain forces of that size on Kyushu. The civilian population would also be extremely hostile and would do everything possible to hinder American military operations.‘1 Precisely what action, if any, the JPS and JCS took on JWPC 235/3 is not clear. Given the similarities between it and the final plans for the invasion of Kyushu, however, it aPpears that JWPC 235/3 was used as a planning guide by the 39 \ Q ‘ Tsuno Hitoyoshi \ \ \ flu“. KOSHIKI C n ETTO : I I POSSIBLE LANDING AFTER , D+15 0 Taniyama D DAY KAGOSHIMA Kamila (9 O O 0Kaneyama xxx UJI GUNTO 0 sows (9 FIELD D DAY _ “R xx WRAILROAD 00 ———MAIN ROAD MAP 2. PLAN FOR THE INVASION OF SOUTHERN KYUSHU (JWPC 235/3) staffs MacArt super: at thr disper beache Airpowl defendc probab thereb; final I larger 4O staffs of Admiral Chester W. Nimitz and General Douglas MacArthur. JWPC 235/3 took full advantage of American superiority in amphibious warfare and firepower. By landing at three different places, it would force the Japanese to disperse their troops to defend all potential landing beaches, thus making it easier to establish a beachhead. Airpower would hinder enemy attempts to reinforce the defenders on the beaches, and at best, the Japanese would probably be forced to commit units to battle piecemeal, thereby limiting their combat effectiveness. Although the final plan for the invasion of Kyushu called for a much larger assault force than that outlined in JWPC 235/3, it still contained the earlier plan's underlying concepts and theories. CHAPTER 4 STRATEGIC ISSUES Shortly after the release of JWPC 235/3, the JCS left for the Second Quebec Conference, code-named OCTAGON, which lasted from 11 to 16 September 1944. The conference had been called by the British to discuss a number of issues related to the war against Japan. The JCS were not too keen about the conference, for they considered it a British attempt to interfere in planning for the Pacific. Churchill was faced with a number of political dilemmas that forced him to ask for a conference. The Americans were making considerable advances in the Pacific, and time was; running out for the British if they wanted to make a“ significant contribution to victory over Japan. Churchill feared that if the British did not do something soon, the United States would later remind the British that "We came to your help in Europe and you left us alone to finish off Japan." If such a thing was allowed to happen, it would have put the British in a disadvantageous position vis-a-vis the United States in the post-war world.1 In terms of a British contribution to the war, Churchill proposed sending the most modern units of the Royal Navy out to the Pacific to operate with the United States Navy, under American command. With Italy out of the war and the Battle of the Atlantic nearly won, much of the Royal Navy was unemployed. King did not think much of the idea. Unlike the U.S. Navy, the Royal Navy had little recent experience in 41 42 conducting sustained operations at sea for long periods without port visits, and as a result had not developed a suitable fleet train of tankers and other auxiliary vessels. King feared that the British would have to rely on the U.S. Navy for logistical support, and the American system had its hands full supporting its own fleet. King believed that the combat strength of the Royal Navy would not compensate for the increased logistical burden. He proposed that it be employed in the Indian Ocean or the Netherlands East Indies, away from the American fleet and closer to bases in Australia and Ceylon.2 King's view of the Royal Navy was a blow to British' pride. He said, in essence, that not only was the Royal Navy not essential in the Pacific, but that its presence would be a liability. Roosevelt, sensitive to British pride, graciously accepted Churchill's proposal to use the Royal Navy in the Pacific. King voiced his objections to the President, but Roosevelt was adamant, and King was forced to concede. King was not a gracious loser, however, and told the British in no uncertain terms not to expect any logistical Support from the U.S. Navy. After developing a fleet trainfand suitable bases, the British Pacific Fleet went on to perform yeoman service at Okinawa and, had the invasion of Japan been carried out, would have taken part.3 In addition to the Royal Navy, Churchill also. proposed sending Royal Air Force squadrons to the Pacific. The Americans were non-commital regarding this offer. Arnold 43 maintained that the United States had enough aircraft available or in production to meet the requirements of the air war in the Pacific.‘ The British proposal involved twenty squadrons of Lancaster heavy bombers, to be based in the Marianas and operated in conjunction with American B—29's. The Lancaster had a shorter range than the B-29, but with mid-air refueling it could reach Japan. Because of this requirement, half of the British aircraft would be fitted as tankers, while the remainder would be combat aircraft.5 The American Air Force did not think much of the idea.} Its senior officers argued that a massive build—up of B-295i was planned for the Marianas, and that there might not be room for a British contingent. They also cited the logistical problems associated with supporting foreign aircraft.6 Consequently, the British proposal was rejected. During the next few months the British and Americans discussed a number of basing options for the British force. By mid-1945 the British were given one of the Ryukyus on which to develop their own airfields. The British also made plans to send medium bombers and fighters to the Pacific, in addition to‘the heavy bombers. All of these aircraft would have been available to support the invasion of Japan. Two convoys carrying construction crews and equipment were enroute to the Far East when the war ended.7 At Quebec the British_ also raised the logistical problems associated with the planned deployment of troops 44 from Europe to the Pacific after the defeat of Germany. They argued that, for planning purposes, a terminal date should be set for the war against Japan. They suggested the goal of defeating Japan within two years after the defeat of Germany, which they believed was flexible enough to allow for any contingencies, such as the demand for occupation troops in Europe. The Americans, who, since the summer of 1943, had been planning to defeat Japan within one year after Germany, saw no real need to change their date. The current schedule called for the invasion of the Tokyo Plain in December 1945, and Marshall believed that it would take three months to: defeat the Japanese. He suggested that the target date be' changed to within eighteen months after the defeat of Germany, which should allow sufficient flexibility in planning. The JCS also recommended that the date be reviewed periodically and adjusted as necessary as the war progressed. The British accepted these recommendations without complaint.8 The Quebec Conference exemplified the nature of the relationship between the United States and Great Britain regarding strategic planning in the war against Japan. In Europe, there was some degree of parity in the relationship between the‘two allies, though because of greater resources, the United States gradually became the dominant partner. There was no such parity in the war against Japan. After the early, frustrating attempts to get the British to play a more active role in Asia, particularly in Burma, the United States devised its own strategy for defeating Japan. If the British 45 wanted to play a part in that endeavor, they would have to conform to American plans and ideas. While the Quebec Conference was in session, a fast carrier task force under Admiral William F. Halsey attacked the central Philippines in support of the forthcoming assault on the Palaus. Halsey found Japanese resistance far weaker than anticipated, and recommended that the Palaus be bypassed and the Philippines invaded immediately. Nimitz insisted on following through with the Palaus operation, but did cancel a planned asssault on Yap. The troops slated for Yap were offered to MacArthur, who, ever anxious to return to the. Philippines, accepted them without a moment's hesitation. Because of this unexpected windfall, MacArthur proposed advancing the target date for the invasion of Leyte by two months, from 20 December to 20 October, which was approved by the JCS. Subsequently, on 3 October, the JCS ordered MacArthur to attack Luzon in January 1945, while Nimitz was ordered to seize Iwo Jima in January and Okinawa in March. With the selection of Luzon, Formosa was no longer considered a primary target. There was not, however, any decision on the specific target to follow Okinawa, in spite of the accepted recommendations of JCS 924 and the existence of JWPC 235/3.’ The JWPC was assigned the task of determining how best to deliver the final blows against Japan, and reported its findings in JPS 404/14 on 7 October 1944. This report was in many ways a repeat of JCS 924. Its authors believed that it 46 was highly improbable that the Japanese would surrender before the industrial area of Honshu was invaded. They rejected a direct assault against Honshu due to expected heavy enemy resistance, thus making the prior seizure of one of the other Japanese islands mandatory, with Kyushu considered the best choice. Hokkaido was ruled out for two reasons. First, the weather would not permit a landing .before May 1945, and second, the assault would have to come from the north, and thus could not take full advantage of the bases and logistics structure developed during the drive through the central Pacific. Nobody was able to predict precisely when the war in Europe would end, so the JWPC assumed that the first forces to be deployed from Europe to the Pacific would arrive in September 1945. Accordingly, they scheduled the invasion of Kyushu for September, and the assault on Honshu for December 1945. Because there was a gap of several months between the Ryukyus operation and the assault on Kyushu, the JWPC considered a number of other operations designed to maintain pressure on the Japanese. Among the possible targets were the Chinese coast, Formosa, and the northern Kuriles, dependent, Of course, upon the availability of forces and the strategic situation.‘0 The report met with a mixed reaction when presented to the JPS. Brigadier General Frank N. Roberts was disappointed by the rejection of Hokkaido as a potential target, for he believed that it might be seized as an intermediate objective 47 between the Ryukyus and Kyushu operations. His colleagues strongly disagreed. Brigadier General W.W. Bessell pointed out that an assault on Hokkaido could not take place before May or June 1945, which would adversely affect the invasion of Kyushu. Commodore E.W. Burrough commented that the six-month period would be better used to reduce Japanese military and industrial strength than to seize new territory. Additionally, he said that an attack on Hokkaido would be extremely difficult due to lack of intermediate bases, good ports, and land-based air support. Rear Admiral Donald GB. Duncan pointed out that an assault on Hokkaido would require_ substantial forces, to the detriment of other operations.f Such an operation would also split the Navy between supporting Hokkaido and the Bonins and Ryukyus'operations.11 Because of the JPS's reaction to the report, the JWPC rewrote it, and placed more emphasis on the disadvantages of choosing Hokkaido over Kyushu. The report also examined the possible seizure of intermediate objectives from which to reduce Japanese military and industrial strength prior to an invasion. Among the potential targets were Formosa, Hokkaido, ~the Chinese coast north of Swatow, and the northern Kuriles. All were substantial undertakings, and would require the use of troops tranferred from Europe. Moreover, such operations would probably delay the invasion 12 of Honshu. The JPS meeting at which the revised version of JPS 404/14 was presented was in many ways a repeat of the first. 48 Brigadier General Richard C. Lindsay, who had been absent from the earlier meeting, questioned why Hokkaido was not considered a suitable alternative to Kyushu. He believed that an invasion of Hokkaido would require smaller forces than generally thought, and that it could be launched in early 1945. Lindsay also pointed out that such an operation would possess the element of suprise, and would provide additional bases from which to bomb the industrial heartland of Japan. In response, Duncan repeated the earlier arguments 13 against Hokkaido. The JWPC revised their report again, to include Lindsay's comments, and upgraded Hokkaido. as an: a l ternative to Kyushu .“ The report was presented to the JCS on 27 October 1944.15 King stated that between the Ryukyus and Kyushu operations, other operations should be conducted to lower Japanese will and capability to resist by tightening the blockade of the Home Islands and increasing air strikes against industrial targets and enemy air and naval forces. King further stated that these measures, on their own, might even be enough to bring about a Japanese surrender without the need for an invasion. He did not, however, consider Hokkaido a suitable target for an assault.‘6 Arnold agreed with King that more air bases were needed to soften up Honshu prior to an invasion. Unlike King, however, Arnold considered Hokkaido to be a viable target and called for its seizure in May 1945. Arnold did not consider the Navy's concern over splitting the fleet to be justified, 49 since the Japanese fleet had been decisively defeated at Leyte and no longer posed a serious threat to American SLOCs. In addition, Hokkaido would offer a line of communication to the Soviet Union when it entered the war.‘7 Because of these comments, the JPS revised the report once more, and presented the new version to the JCS on 23 November. In it, the JPS cautioned that the undertaking of any extensive operations prior to the arrival of troops from Europe would probably delay the invasion of Honshu. Such a delay might not be all bad, since it would allow additional time to reduce Japanese military and industrial strength. In such an event, the planners considered Hokkaido a potential' target, though an invasion could not be carried out until May or June 1945, and in any event an invasion would have to rely on carrier-based air support. Formosa was another possible target, but the northern Kuriles were crossed off the list. Possession of the Kuriles might be useful to support the Soviets, but it would make only an indirect contribution to the main campaign, and consume resources that could be better applied elsewhere. Objectives on the Chinese coast were also considered, though they would have to be limited to small lodgments in order to avoid being drawn into a major campaign.18 The JCS approved the report as a guide for future planning. Following the seizure of the Ryukyus in March 1945, certain operations (as yet unspecified) would be carried out in June, to be followed by the invasion of Kyushu 50 in September 1945 and of the Tokyo Plain in December 1945. The timing of the last two operations would be dependent upon the arrival of troops from Europe and the success of previous operations in reducing Japanese will and ability to resist.‘9 The debate that surrounded JPS 404/14 did not materially affect the strategy previously outlined in JCS 924. It did, however, reopen the question of Hokkaido as a potential target. The Army and the Navy had almost completely opposite view on the subject. The Navy ruled out Hokkaido because of‘ lack of good ports and, perhaps more importantly, lack of intermediate bases. From the Ryukyus to Hokkaido is a distance of more than 1,300 miles, which, in the opinion of the Navy, would make it extremely difficult to support the fleet. Strategically, the Navy was also concerned over splitting the fleet between the Bonins-Ryukyus and Hokkaido. Kyushu was in most ways a much better target than Hokkaido. It was closer to the planned baSes in the Ryukyus and contained an excellent fleet anchorage and numerous existing airfields, as well as a number of potential airfield sites. Also, according to a report by the Joint Intelligence Committee (JIC), there would be little difference in initial Japanese resistance to assaults on either Kyushu or Hokkaido. The enemy, would, however, be able to reinforce Kyushu much more easily than Hokkaido. On the whole, therefore, Kyushu was a logical choice.“ The Army position was based on the premise that Kyushu might not always be a good target. Once American forces were 51 established in the Ryukyus, it would become more and more obvious to the Japanese that Kyushu would be the next likely target for an assault. They would, therefore, increase their forces on the island to prevent a successful landing. In such a case, it would not be tactically sound to attack at a point of enemy strength. Because of the threat to Kyushu, other areas of Japan might be less heavily defended, probably among them Hokkaido. If a lodgment could be gained on Hokkaido at less cost than Kyushu, it would be a sound move. As for the Navy's objection about the lack of intermediate bases, the Army could always point to the successful landingsf in Morocco in November 1942 (Operation TORCH), for the: invasion forces had sailed all the way from the east coast of the United States without needing any intermediate bases. In the meantime, the Navy had gained considerable experience in amphibious warfare and sustained operations at sea. The Army and Navy saw the problem from different angles, which seemed to be irreconcilable. Much of this was based on ignorance of the professional aspects of the other's area. There was, however, a possible solution to the dilemma, but for some reason both parties were blind to it. Across Tsugaru Strait from Hokkaido was northern Honshu. This area offered something for everyone. For the Navy, there was the fine anchorage of Mutsu Bay. For the Army Air Force, there were a number of existing airfields and potential sites for others, all within range of the industrial heartland of Japan. For the Army, the area would probably be lightly 52 defended, thereby improVing the odds for a successful assault. Strategically, an attack on northern Honshu would isolate Hokkaido from the rest of Japan and open SLOC's to the Soviet Union. An assault here would also possess the element of suprise, and would no doubt disrupt Japanese defensive dispositions, which were assumed to be based on an assault on southern Kyushu. There were a number of problems, such as a cool climate, distance from the nearest American base, and the necessity to rely solely on carrier-based air support during the assault phase, but it was a viable alternative to southern Kyushu. However, nobody seemed to; appreciate these things until near the end of the war, whenf preparations were in full swing for an assault on southern Kyushu.21 CHAPTER 5 COMMAND REORGAN I ZAT ION During late 1944 and early 1945 the JCS had to deal with another problem related to the invasion of Japan: who would be in overall command of the operation? Due to interservice rivalries, there was no supreme commander in the Pacific. Instead, there were two area commands: Pacific Ocean Areas (POA) under Nimitz, who was also Commander-in-Chief, Pacific Fleet (CINCPAC); and the Southwest Pacific Area (SWPA), under MacArthur. Under normal circumstanes, MacArthur, by virtue of his seniority, would have been appointed overall commander in the Pacific. Thej Navy objected, however, to an Army officer having control off the bulk of its fleet. The arrangement, as awkward as it seems, managed to work quite well and served as the basis of the two-prong Pacific offensive. The prospect of the invasion of Japan, however, forced a reevaluation of the command set-up. By early 1945 some officers in the Army and Navy began to think seriously about the command setup, with the Army more interested in the matter. The Army opposed the idea of the massive land battles on Kyushu and Honshu under the control of a naval commander. There was also the question of what to do with MacArthur. Once Luzon was seized, he would have reached the northern limits of the SWPA. Would he be given authority beyond those limits, or would he be relegated to command a series of mopping-up operations in the 53 54 Netherlands East Indies? The matter was further complicated by MacArthur's status as one of the few five-star officers in the American armed forces. During the summer and fall of 1944 both MacArthur's and Marshall's headquaters advocated the idea of restructuring Pacific commands by placing all army forces under a single commander. Naval forces would be similarly organized, though this would not be a drastic change, since as CINCPAC Nimitz already had operational control of all naval forces in the Pacific. The Army General Staff worked on the matter with the intention of presenting a report to the JCS, though: nothing was ever completed. In August, the JWPC suggestedf that the Joint Strategic Survey Committee (JSSC) study .the problem, with the idea of creating a single supreme commander for the entire Pacific. Nothing came of the JSSC's study, since the JPS showed no interest in the matter.1 The JCS first discussed the command issue in September 1944, in connection with the debate over whether Luzon or Formosa would be taken first. Marshall recommended that all Army forces in the Pacific be placed under a single commander, which would, in his opinion, make the best use of available resources. MacArthur would have command of all troops, with the exception of specific units allotted to Nimitz for defense and logistics duties. King objected to Marshall's proposal, since it would give the Army influence over the Formosa operation, and Formosa was within the Navy's sphere of influence. King recommended that if there was a 55 unification of command in the Pacific Nimitz be appointed as supreme commander. On that note the JCS dropped the matter and went on to other issues.2 MacArthur was one of the key figures in the debate, for his future was at stake. Given the existing command structure, he feared that he would be relegated to overseeing operations in the Philippines and the Netherlands East Indies, away from the decisive battles in Japan, while Nimitz would have overall command of the invasion.3 To prevent a potential fall into obscurity, in mid-December MacArthur eXpressed his views on the command problem to Marshall as "aj matter of the most immediate and gravest urgency." With' massive ground operations in the future, MacArthur went on to say that "we are so handicapped by the artificial area boundaries and command that the ultimate success of the war against Japan is in gravest jeopardy." He recommended that all naval and army forces be placed in separate commands, both under control of the JCS. The JCS would appoint commanders for specific operations on the basis of which service had the greatest interest and involvement.4 Marshall replied to MacArthur that the General Staff was already working on a similar proposal and planned to present it to the JCS. MacArthur repeated his earlier arguments, and stated that, if the JCS could not reach a consensus on the issue, it "be placed before The President so that the responsibility for what may happen may not rest upon the Army." In spite of MacArthur's exhortations, it was some 56 time before the JCS studied the command problem. During December they were preoccupied with the Battle of the Bulge, which required forces slated for transfer to the Pacific. This delay might well prolong the war in the Pacific. The JCS also delayed action to see what the results were of the upcoming Yalta conference, and how Soviet entry into the war would affect the strategic situation in the Far East.5 Nimitz joined the debate in late January 1945. In a letter to King, he recommended that the entire Pacific area, with the exception of Japan, form a single theater under unified command. Nimitz went on to propose that, "When landj operations involving large armies are undertaken in Japan; the land area of Japan sould constitute a new theater with a theater commander responsible to the Joint Chiefs of Staff." Any amphibious operations would be under control of the Navy. Nimitz's proposal was well-received by the Navy's War Plans Division, but it was never presented to the JCS for debate.6 On 26 February 1945 Marshall finally brought the command issue before the JCS. He recommended the adoption of the earlier Army concept of separate Army and Navy force commanders; with each planning and conducting his part of the war under the direction of the JCS. The JCS would appoint commanders for major operations. Lieutenant General Barney M. Giles, who represented Arnold at the meeting, expanded on Marshall's idea and proposed the creation of a single unified Command in the Pacific. If Marshall's proposal was adopted, Giles recommended that the 20th Air Force (the Marianas-based 57 B-29's) remain under the direct command of the JCS.7 King presented his views on the proposed reorganization at a closed meeting of the JCS on 8 March. He stated that the command question could not focus solely on the forces involved, but must also include responsibility for specific operations. King first listed a number of operations for Nimitz and MacArthur to conduct in China and the East Indies. He then put forward Nimitz's proposal for the creation of a third theater command in the Pacific, which would be responsible for the invasion of Japan. The new ’Japan Area (JAPA) would encompass the four main islands of Japan.fl CINCJAPA would have administrative control of all Army forces; in the Pacific, with the title Commanding General, Army Forces, Pacific. He would prepare plans for the invasion, coordinating with CINCPOA on the naval and amphibious aspects of the plan, and would also assign troops to CINCSWPA and CINCPOA as required for their missions.8 Marshall disagreed with King's position on a number of points. First, he stated CINCJAPA should have jurisdiction over certain areas outside of Japan, such as the Ryukyus, in order to control the land-based air forces that would play a vital role in the invasion. Marshall was also skeptical about the value of some of King's proposed operations, which included possible landings on the China coast. King maintained that such operations would provide bases from which to bomb and blockade Japan, but Marshall replied that they would divert resources that would be better employed in 58 an invasion of Kyushu. Lastly, Marshall maintained that the creation of a new theater command would do little to solve the problem of allocation of resources; in fact, it might further complicate things. Marshall presented the Army's proposal for the command reorganization, which designated Nimitz as overall naval commander and MacArthur as overall army commander in the Pacific. The JCS could not reach a consensus on the various proposals, however, and referred the matter to the JPS for "study and report."9 The JPS studied the relevant documents for a week but did not reach a consensus. They interpreted the Jointj Chief's order literally, and did not attempt to reach af solution. Discussions between Admiral Duncan and Brigadier General George A. Lincoln, however, did more clearly define the areas of disagreement between the various service proposals. They reported their conclusions the JCS on 16 March. They said that the Navy proposal would make the theater commanders responsible for operations, while the Army and Navy force commanders had primarily administrative and logistical responsibilities. The Army version, on the other hand, placed full operational and administrative control of forces in the hands of the two theater commanders, Nimitz and MacArthur.‘o During the remainder of March the JCS continued to debate the command issue. Marshall maintained that all Army forces in the Pacific should be placed under a single command, and was intent on preventing naval command of the 59 invasion of Japan. King argued the Army proposal would rob CINCPOA of the troops needed for execution of the Ryukyus campaign, as well as the planned operations in China. He also continued to press for the formation of a third theater command to oversee all aspects of the invasion of Japan. At one point during the debate, when there seemed to be no prospect of a resolution, King proposed that solution of the command issue be deferred to a later date. The Army, however, opposed King's move and insisted that the problem be dealt with at once, not at some vague date in the futuref” On 3 April the JCS finally reached a consensus and: issued a directive which set forth the new command structure.j In essence, the Army proposal was adopted. MacArthur was designated Commander-in-Chief, U.S. Army Forces, Pacific (CINCAFPAC), in addition to his position as CINCSWPA. Nimitz retained his position as CINCPAC and CINCPOA. The JCS would issue operation orders, assign missions, and designate commmanders for major operations. King feared that Nimitz would be removed from command of the Ryukyus operation because of the new command structure, since large Army forces were involved. To assuage such fears, the JCS directive included a ‘provision which stated that the two theater commanders would still control another service's forces currently assigned to them, until such time as they were assigned elsewhere by mutual agreement or by JCS order.‘2 In addition to delineating the new command structure, the directive set forth new missions for Nimitz and 6O MacArthur. Nimitz would carry out the seizure of the Ryukyus, continue planning for landings in China in the vicinity of Shanghai, and support MacArthur's operations in the Philippines and East Indies. MacArthur would complete the occupation of Luzon and conduct other operations in the Philippines and on Borneo. More importantly, both commanders would begin planning and preparations for the invasion of Japan, coordinating their efforts where necessary. The JCS directive also stated that the 20th Air Force would remain under command of Arnold in Washington, an arrangement that was becoming increasingly awkward. By late] spring 1945 there were some 800 B-29's in the Pacific, land. they were dependent upon the theater commanders for support. In Arnold's opinion, the Washington headquarters could no longer effectively deal with the inevitable conflicts in priorities that would occur with the theater commanders. He recommended the transfer of the B-29 command to the Pacific. He also proposed the establishment of a single strategic bomber command for the entire Pacific, to be designated U.S. Army Strategic Air Force (USASTAF) and equal to the other commands. Such an arrangement would make it easier for the prospective‘USASTAF commander, General Carl Spaatz, to deal with his Army and Navy counterparts.‘3 Under Arnold's proposal, USASTAF would be independent of both CINCPAC and CINCAFPAC, would cooperate with them, and would have an equal voice regarding allocation of shipping resources. Leahy objected to USASTAF's independent status. um ‘1U..-i-. ‘1 3.11 : 61 He believed that in the interest of efficiency, USASTAF should be placed under the jurisdiction of CINCAFPAC, since the airpower would be employed in support of the land campaign in Japan)‘ After a JCS meeting on 29 May 1945, Arnold withdrew his proposal and presented a new one. Instead of creating a new command, he proposed that 20th Air Force headquarters be .tranferred to the Pacific and designated USASTAF. Under this system, the existing XXth and XXIst Bomber Commands would become the 8th and 15th Air Forces, respectively. USASTAF would be available to Nimitz and MacArthur upon request. Before making the change, however, King recommended that Nimitz and MacArthur be given an opportunity to express their opinions. Nimitz saw nothing wrong with Arnold's new proposal, but MacArthur had doubts. In his opinion, the proliferation of air commands in the Pacific--the Far East Air Force, the Strategic Air Force, and Navy and Marine air forces--complicated the employment of forces and selection of targets. He proposed that all land-based airpower be placed under a single command, which could more effectively coordinate‘the air war against Japan. This command would no doubt come under MacArthur's jurisdiction as CINCAFPAC.15 Arnold maintained that Spaatz's presence would make the problems MacArthur described more manageable. King 'stated,however, that MacArthur had raised some valid concerns that needed to be addressed. King did not consider the "a: ..i'. 62 placement of all land-based air forces under a single command desirable, possibly because some Navy forces were involved. He also pointed out that the plans for the invasion of Japan assumed the existence of the current command structure regarding the 20th Air Force. In King's opinion, the simplest solution was to transfer 20th Air Force headquarters to the Pacific, where it could work more closely with Nimitz and MacArthur. There was no need to create a USASTAF.‘6 Arnold made an inspection tour of the Pacific during June, which convinced him all the more of the need for 'an independent USASTAF. At a JCS meeting on 2 July, he once again proposed the creation of the USASTAF. This time his idea met with a good reception, and a directive outlining the reorganization was sent to the Pacific commanders the following week. USASTAF was charged With "the conduct of land-based strategic air operations against Japan with the object of accomplishing the progressive destruction and dislocation of Japan's military, industrial and economic systems to a point where her capacity for armed resistance is fatally weakened." USASTAF would be independent of the other Pacific commands, but was required to cooperate with them and rely upon them for logistical support.‘7 With the establishment of USASTAF, the command structure that would have overseen the invasion of Japan was in place. It is impossible to predict just how well the new system would have worked, since it was never put to the test. No doubt there would have been some strain and friction, which 63 was to be expected with three services competing for limited resources, prestige, and responsibility. Some of these problems would appear, for example, in the drafting of the directive for the invasion of Kyushu. It would have been up to the JCS, and possibly, the President, to resolve any conflicts. CHAPTER 6 THE DECISION TO INVADE While the debate raged over changing the command system in the Pacific, other events took place that would also affect the invasion of Japan. At the Yalta Conference in February, Stalin guaranteed that the Soviet Union would enter Gthe war against Japan within three months after the defeat of Germany. This commitment solved a number of problems that had plagued American planners during the war. Soviet forces would fix, engage, and destroy Japanese troops in Manchuria and Korea, thereby making them unavailable for the defense of Japan. This would eliminate the possible need for an] American invasion of the Asian mainland to defeat anyf Japanese forces that might not obey a surrender order issued by Tokyo. Lastly, it would deny the Japanese government a place of refuge and the resources necessary to continue the war if the Home Islands became untenable.‘ American troops landed on Okinawa on 1 April, which marked the beginning of a savage struggle to seize the key island. The JCS had not yet decided what course of action to follow after the completion of the Ryukyus campaign, and were divided over the need for an invasion of Japan. Leahy and King were not completely convinced that an invasion was necessary. They maintained that a very intensive blockade and bombing campaign of Japan would be sufficient to bring about an unconditional surrender. They advocated gaining additional positions in the Ryukyus and lodgments on the 64 65 China coast in order to tighten the blockade. Leahy and King did not vigorously oppose the idea of an invasion during JCS meetings, but instead left the impression that they were not enthusiastic about the idea, and that they were unconvinced by efforts by the JPS's justifications for an invasion.2 In late April the JPS prepared a report for presentation to the JCS, which reiterated the need for an invasion. They maintained that blockade and bombardment, by themselves, would not bring about an unconditional surrender, but at best a negotiated peace. Such a strategy might require considerable time to achieve an outcome, which meant that] Japanese tenacity might eventually undermine American will tof pursue unconditional surrender at any cost. An invasion, on the other hand, had a greater potential to force an unconditional surrender. Even if it did not accomplish that goal, it would result in the utter and complete destruction of Japan's means to resist.3 Current intelligence estimates also favored invasion. The blockade and bombardment of Japan would have resulted in the destruction of industry and shortages of raw materials. Troop transfers from the mainland would amount to no more than one diVision a month because of shipping shortages. The Japanese navy and air force had little potential to offer sustained resistance, and would be reduced to employing suicide tactics against vastly superior Allied forces. Once a lodgment was established in Japan, the Allies could continue to pour in forces until the Japanese were 66 overwhelmed.‘ One of the greatest arguments against an invasion was the dreaded prospect of heavy casualties. The planners did not attempt to make any precise estimates on casualty levels, but they did speculate on possible casualty figures during various phases of the invasion. In seven previous amphibious operations in the Pacific, casualties amounted to 7.45 per .thousand per day, and the planners estimated that the casualty figures for the initial assault on Kyushu would be similar. Once the troops were established ashore, the casualty level would be dramatically reduced. The JPS based. this assumption of the costs of protracted campaigns in: Europe, where casualties amounted to 2.16 per thousand per day. The JPS concluded, therefore, that there should be as few amphibious operations as possible, and that casualties during the land campaign would be acceptable.5 The JPS also maintained that the invasion of Japan would make better use of American resources. In their opinions, the effects of the blockade and bombardment would create a situation favorable for an invasion by December 1945. Sufficient troops and other resources would be avaiable by that time. ‘The JPS estimated that thirty-six divisions would be needed for operations against Kyushu and the Tokyo Plain, and that operations might be completed as early as June 1946. On the other hand, operations along the periphery of the Japanese empire, such as Leahy and King advocated, might require as many as twenty-eight divisions, and would probably 67 prolong the war until the fall of 1946.6 Finally, the JPS concluded that the invasion of Kyushu and Honshu would make the seizure of bases in eastern China unnecessary, probably result in the surrender of Japanese forces in China, and also reduce the likelihood of becoming militarily involved in the dispute between the Kuomintang and the Chinese Communists. In addition, control of the air from bases in Japan would interdict the movement of troops between the mainland and Japan, thus making it unnecessary for a Soviet presence in Manchuria to contain the Kwantung Army.7 The JPS recommended intensifying the blockade and; bombardment of Japan, execution of only those operations that] would help create favorable conditions for an invasion, invasion of Japan at the earliest practical date and seizure of key areas to bring about an unconditional surrender and complete occupation of the islands. They also recommended that a "declaration of intentions" be issued to the Japanese government in order to inform it what lay in store if it continued to resist, as well as to state what would be involved in an unconditional surrender.a The JCS accepted the report as a guide for planning. King was the only member to comment on it. He agreed with the report's conclusions, but found fault with the discussion of potential casualties. He stated that the comparison between European and Pacific operations was invalid, since there were great differences in the type of warfare in the two theaters. He thought it was foolish to justify an 68 invasion with such an argument.9 King was still not completely convinced of the need for an invasion and still maintained that tightening the blockade and increasing pressure on Japan would bring about a surrender without resorting to an invasion. He did, however, recognize that Nimitz and MacArthur needed a definite objective in order to make future plans. In late April King suggested that Nimitz and MacArthur be directed to begin planning and preparations for an assault on Kyushu, code-named OLYMPIC, with a target date of 1 November 1945. In King's view, there was little harm in planning .for and invasion. If the strategic situation warranted, thef operation could be cancelled as late as August or September.‘0 The JPS began work on a directive for the invasion of southern Kyushu, code-named OLYMPIC. The objectives of OLYMPIC were, in order of priority, to increase the blockade and bombardment of Japan, to engage and destroy major enemy forces, and to obtain positions from which to support further attacks against the industrial heartland of Japan. MacArthur was assigned responsibility for ground operations, and would cooperate with Nimitz regarding the naval and amphibious aspects of the campaignJ‘ The Army and Navy planners disagreed over Nimitz's role in the operation. He would be responsible for the naval and amphibious phases of OLYMPIC, but there was some question over how they would be conducted. It was the Army's position that, given the size and nature of OLYMPIC, "the battle in 69 Kyushu is primary and all phases of the campaign must be built back from and must be adjusted to support this battle." The Army recommended, therefore, that CINCPAC's conduct of the naval and amphibious phases of the operation be "in conformity with CINCAFPAC—CINCSWPA'S plan for the campaign on land." In essence, this would give MacArthur overall command of OLYMPIC, something to which the Navy vehemently objected.‘2 While the Navy admitted that "plans and preparations must be built back from the land campaign adopted, and that plans for the naval and amphibious phases of the campaign must take account of and support the plans for the land' campaign," it also believed that "the land campaign adopted. must be one that fits in with the practical aspects and possibilities of the amphibious operations." The Navy recommended a division of responsibility for OLYMPIC, with MacArthur in command ashore and Nimitz in command at sea. This system had worked well in previous landings in the Pacific, and the Navy believed it would also work for OLYMPIC. Nimitz and MacArthur would cooperate and coordinate their planning and preparations for the invasion, thereby ensuring adequate integration of resources and the success of the operatio‘h.‘3 The JPS were unable to reach an agreement over the command relationships for OLYMPIC, so they referred the matter to the JCS, who also had difficulty in reaching a solution. At one point, King suggested that Nimitz and MacArthur simply be directed to invade Kyushu on 1 November. 70 He saw this as no great problem, since earlier Nimitz and MacArthur had been ordered to begin planning and preparations for the invasion. Any problems they were unable to resolve would be referred to the JCS.‘4 Marshall disagreed with that approach. He maintained that if the JCS could not solve the problem, the theater commanders probably could not either. Marshall also stated that the directive setting forth the command reorganization gave the JCS the power to appoint commanders for specific operations. Since OLYMPIC was primarily a land campaign, Marshall maintained that MacArthur should be givenj the overall command, including "control of the amphibiousf assault through the appropriate naval commander."15 Naturally, King objected to anything that would put the Pacific Fleet under Army command. He saw the naval and amphibious phases of the invasion as being dependent upon the ability of the Navy to control the SLOCs. to the western Pacific, which required virtually the entire strength of the Pacific Fleet, under Nimitz's command. Therefore, Nimitz should also be responsible for the naval and amphibious phases of the invasion. King recognized the importance of the land campaign, but maintained that cooperation and coordination by the respective naval and ground force commanders would be enough to ensure the success of the 16 operation. Since Marshall and King could not reach an agreement, they brought the matter before the entire JCS. After much 71 debate, a compromise was reached and a directive for the invasion of Kyushu was sent to MacArthur (CINCAFPAC-CINCSWPA), Nimitz (CINCPAC-CINCPOA), and Arnold (CG 20th AF) on 25 May. The directive amounted to a victory for the Navy. It assigned MacArthur "primary responsibility for the conduct of operation OLYMPIC including control, in case of exigencies, of the actual amphibious assault through Ithe appropriate naval commander," and assigned Nimitz responsibility for the naval and amphibious phases of the operation, while Arnold would "cooperate in the plans, preparations, and execution of operation OLYMPIC and in thef continuance of the campaign in Japan." The JCS directed that] the 20th Air Force would come under command of one or the other of the theater commanders as required.‘7 The directive for OLYMPIC was rather straightforward, with the exception of the provision allowing MacArthur to control the amphibious assault, for it did not specify what "exigencies" would allow MacArthur to take command. Sooner or later the JCS might have had to address this matter. The probable reason why the JCS did not specify the exigencies is that it wou1d have triggered a lengthy debate, thereby delaying thé' issuance of the directive, or possibly no directive at all. With the issuance of the OLYMPIC directive, planning and preparation began in earnest for the invasion. The directive did not, however, irrevocably commit the United States to an invasion of Japan. Everyone concerned understood that the 72 plans were subject to review, or even outright cancellation, if the situation warranted. It is difficult to say precisely when the final approval for OLYMPIC would have been given, but it would probably would have been no later than early October, about the time the assault troops would have been getting ready to board the transports. On 18 June 1945, President Harry S. Truman, preparing for the upcoming Potsdam conference, met with the JCS, Secretary of War Henry L. Stimson, and Secretary of the Navy James V. Forrestal to discuss the necessity for an invasion of Japan. Everyone knew that an invasion would be costly in] American lives, and Truman wanted to know the options: available to bring about an unconditional surrender by the Japanese .18 Marshall, who had long ago admitted the necessity for an invasion, described the assault on Kyushu as "essential to a strategy of strangulation" and as the "least costly worth-while operation following Okinawa. He also stressed that the 1 November target date for OLYMPIC was extremely crucial to a quick end to the war. Any delay would give the Japanese more time to prepare their defenses. Deteriorating weather after the beginning of November might well delay the invasion, and hence the end of the war, by as much as six months.‘9 Marshall also addressed the subject of casualties for OLYMPIC, something on everybody's mind. He cited a study by the Army General Staff, which estimated that American 73 casualties would be around 31,000, roughly comparable to losses during the Luzon campaign. There was plenty of maneuvering room for the Kyushu operation, both afloat and ashore. MacArthur would be in command of the land campaign, and during his earlier campaigns in the Pacific had acquired a reputation for being economical in expending Allied lives. For instance, during the period 1 March 1944 through 1 May 1945, which included the seizure of the Marianas, the Philippines, Iwo Jima, and part ofi the Okinawa campaign, American forces under MacArthur's command suffered 13,742 killed, out a total of 63,510 American casualties .in the- entire Pacific theater.2° To support this position, Marshall read a telegram from MacArthur. He considered OLYMPIC "as the most economical one in effort and lives that is possible." He also commented on the merit of some of the preliminary operations that had been suggested, such as King's idea of landings in China. MacArthur believed that such operations would contribute little to the defeat of Japan, but instead cause the wasteful expenditure of American lives and resources.21 Marshall concluded that the Kyushu operation was the only course to pursue, since the bombardment of Japan would not be enough to bring about a surrender.> He maintained that an invasion "offered the only way the Japanese could be forced into a feeling of utter helplessness," and that, while OLYMPIC would be a difficult operation, it would be no more difficult than the invasion of Normandy.22 74 King spoke next. He said that he agreed with Marshall, and that the more he studied the matter, the more impressed he was with the strategic location of Kyushu. Kyushu seemed to be a logical follow-on target after Okinawa, and was essential to bring about the unconditional surrender of Japan. In King's opinion, the invasion of Kyushu should proceed without delay. Afterward, it would be necessary to judge the effect of any possible operations by the Soviets or Chinese on Japanese will to continue the war, as well as the necessity for the invasion of the Tokyo Plain.23 While King claimed to have agreed with Marshall over the invasion of Kyushu, one must suspect his sincerity. As shown- in earlier episodes and in his memoirs, King was never wholly convinced on the need for an invasion. His claim of agreement with Marshall may have been a front, in order to give the President the impression of solidarity among the JCS. King could have spoken his mind at the meeting, but chose not to do so. Truman then asked for Leahy's views on the subject. Leahy raised the issue of casualties again. He stated that the Okinawa campaign had resulted in casualties of about 35%, and feared that the invasion of Kyushu would produce similar figures. He wanted to know how many troops were slated for the invasion, in order to get some idea of. what sort of casualties to expect." Both King and Marshall answered this question. King believed that one could not draw an analogy between Okinawa 75 and Kyushu. At Okinawa, the assault forces were limited to the choice of one assault area, as well as a frontal attack against strong enemy positions. At Kyushu there would be simultaneous landings on three widely separated fronts, which would force the enemy to disperse his forces. Additionally, there was plenty of territory for maneuver, instead of a frontal assault like Okinawa. King estimated that casualty figures for OLYMPIC would fall somewhere between the figures for Luzon and Okinawa (31,000 to 41,700).25 Marshall stated that 766,700 troops would be involved in the assault on Kyushu. The Army estimated enemy opposition. at eight divisions, for a total of 350,000 troops. Hef believed that the Japanese would have great difficulty in transporting reinforcements from other parts of Japan to Kyushu because of heavy American attacks on Japanese LOCs prior to the invasion.26 Lieutenant General Ira C. Baker, who represented the Air Force at the meeting, stated that he and Arnold agreed with Marshall about the need for an invasion. Airfields on Kyushu were essential to an intensive bomber offensive against industrial targets elsewhere in Japan, as well as to provide direct support for the invasion of the Tokyo Plain. Eaker also said that airpower alone could not defeat Japan, and that the presence of ground troops would aid the air forces by reducing the number of sorties required, with a reduction in losses.27 Both Forrestal and Stimson agreed with the JCS over the 76 need the invade Kyushu. Forrestal considered the invasion essential, no matter what military course of action was chosen, and recommended that it be launched as soon as possible. He said that even if the United States wanted to lay seige to Japan for a year and a half or so, it would still be necessary to invade. While endorsing the invasion, Stimson also urged Truman to pursue a political solution to .the war. Stimson believed that there were many people in Japan who disapproved of the war, but had kept silent on the matter to avoid prison or assassination. Diplomatic measures might bring the opinion of these people to the surface and” possibly force the Japanese government to sue for peace. Anf invasion, on the other hand, might force these people to take up arms against the invaders. Having heard from his principal military advisors, Truman agreed that planning and preparations for OLYMPIC should continue, while the decision to proceed with the invasion of the Tokyo Plain would be deferred until after the effects of OLYMPIC were assessed.28 Another topic at the meeting was American relations with the British and the Soviets in the war against Japan. Truman asked whether it was desirable to appoint an overall Allied commander in‘the Pacific. Both King and Marshall stated that such a combined command would only complicate matters and probably prolong the war. As for the Soviets, King mentioned that, while their entry into the war against Japan was desirable, it was by no means essential. He cautioned Truman not to beg the Soviets to enter the war, or else they would 77 gain considerable leverage in the shaping of post-war Asia. King believed that the United States could defeat Japan without Soviet assistance, though the cost would be greater. He may have seriously underestimated just how costly it would have been, since it might have required a large American involvement on the Asian mainland to destroy any Japanese forces which refused to surrender. There was also the ominous prospect of becoming embroiled in the Chinese civil war.29 In asking the JCS about the desirability of a combined command in the Pacific, Truman may have anticipated a British' attempt to be more involved in the final phases of the war in- the Pacific. In early July, shortly before the Potsdam conference, the British proposed that the CCS be granted overall jurisdiction over strategic planning in the war against Japan. The JCS would act as agents of the CCS in prosecuting the war in the Pacific and China.30 The JCS rejected the British proposal at Potsdam, stating that the . Pacific and China were areas of American interest, and that participation of the CCS in the planning process for those areas would "involve added complications."31 The British asked the Americans to reconsider their Position. They stated that British forces would be involved if! the invasion of Japan, and that they should have a voice 111 the planning for the invasion. The British also attempted 11> assuage American fears that they would try to interfere at thee operational level. Despite their appeal, the American 78 position did not change.32 During the summer of 1945 American forces stepped up their attacks on Japanese military and industrial targets as a prelude to invasion. Attacks by Navy aircraft on Japanese naval bases destroyed most of the Imperial Navy's remaining large warships, while Allied warships shelled coastal targets with impunity and Air Force B-29's continued to level Japanese cities. Japanese response to these attacks was minimal, for they were conserving their dwindling military resources for the expected invasion of the homeland. On 6 August the city of Hiroshima became the first' target for a nuclear weapon, with Nagasaki suffering a' similar fate three days later. On 8 August the Soviets, in keeping with their earlier commitments, entered the war against Japan with a massive invasion of Manchuria. These events, together with the Emperor's intervention in the affairs of state, led to an unconditional surrender by Japan on 2 September 1945.33 CHAPTER 7 "OLYMPIC" When the war ended planning and preparations for OLYMPIC were well-advanced. While Nimitz and MacArthur had overall responsibility for OLYMPIC, they vested operational control in subordinates: Admirals William F. Halsey, Jr., and Raymond A. Spruance, and Generals Walter E. Krueger and George C. Kenney. In many ways the plan for OLYMPIC was similar to JWPC 235/3, but there were a number of differences. While JWPC 235/3 envisioned an assault by eight divisions, OLYMPIC called for the employment of more than thirteen divisions. There were other differences, such as‘ the size of the lodgment on Kyushu and the choice of landing- beaches, but in general OLYMPIC was an outgrowth of JWPC 235/3. The first, or Preparation, phase of OLYMPIC began in late July, with air and naval bombardment of a variety of targets by Halsey's Third Fleet. Third Fleet contained seventeen aircraft carriers, eight battleships, twenty cruisers, and seventy-five destroyers. Between X-75 (28 July) and X-8 (23 October), Halsey's forces were to reduce Japanese air and naval forces and merchant shipping and disrupt enemy lines of communication between Honshu and Kyushu. Between X-14 (18 October) and X-8 Halsey's carriers would attack targets in southern Honshu, Shikoku, and Kyushu in order to isolate the invasion area. On X-8 two carrier groups would be detached from Third Fleet and assigned to 79 80 Spruance's Fifth Fleet to participate in the pre-invasion bombardment of the assault area. The rest of Halsey's forces would continue to attack targets away from the invasion area.‘ For the most part, Third Fleet would operate east of a line between Kinosaki on the northern coast of Honshu and the eastern tip of Shikoku. Air strikes west of that line would be carried out by Kenney's Far Eastern Air Force (FEAF), consisting of the 5th, 7th, and 13th Air Forces and the 2nd Marine Air Wing (MAW). FEAF, operating from bases in the Ryukyus, would interdict communications between the invasion area and northern Kyushu, attack possible staging areas for' enemy reinforcements, and make diversionary strikes along the- Chinese coast. Once airfields on Kyushu were in American hands and enough aircraft based at them, FEAF would relieve the Navy of responsibility for close air support for the ground forces. The B-29's of the USASTAF under Spaatz also had a role in OLYMPIC. Under Air Force doctrine these aircraft were intended for use against "strategic" targets, such as specific installations on Kyushu, the mining of Shimonoseki Strait between Honshu and Kyushu, and, after X-30, the bombardment‘and isolation of the Shanghai area in order to interdict the transfer of troops from the mainland to Kyushu. The B-29s of Lieutenant General Nathan F. Twining's 20th Air Force could be employed in direct support of the invasion if ordered by the JCS.2 The amphibious phase of OLYMPIC would be carried out by 81 Spruance's Fifth Fleet. This was the first time that Third and Fifth Fleets had existed simultaneously, since they had previously existed as administrative designations for the same groups of ships (Third Fleet when under Halsey and Fifth Fleet when under Spruance). This was also the first time Halsey and Spruance had commanded at sea together since the carrier raids of early 1942. Admiral Richmond K. Turner's Advance Force would arrive off the invasion area on X-8. While aircraft from Vice Admiral Frederick C. Sherman's Fast Carrier Force achieved and maintained air superiority, aircraft from Rear Admiral- Calvin T. Durgin's Escort Carrier Force would begin to soften' up the beaches, destroy coastal defenses, and interdict the movement of enemy reinforcements into the invasion area. At the same time the Support and Covering Force would begin its shore bombardment of selected targets and would cover Rear Admiral Alexander Sharp's minesweepers as they cleared the waters around the assault area.3 The ground forces consisted of I, IX, and XI Corps, 40th Infantry Division, and the 158th Regimental Combat Team (RCT) of the Army and the V Marine Amphibious Corps (MAC),totalling 551,580 men. The strength of this assault force fell considerably short of the 766,700 men originally slated for the invasion, the figure cited by Marshall to Truman at the June meeting. There were a number of reasons for this shortfall. Heavy fighting in the Philippines and at Okinawa had produced casualty levels higher than anticipated. This 82 was further compounded by the difficulties the Army was experiencing during the later stages of the war in providing replacements for combat casualties. This was due to reduced draft quotas in order to minimize the problems associated with post-war demobilization. Other units in the Pacific could have been drawn upon to bring the assault forces up to strength, but this was not done because of the possible adverse effect on the planned invasion of the Tokyo Plain. The second, or Assault, phase of OLYMPIC would begin on X-S (27 October), when Rear Admiral Glenn B. Davis' Western Attack Force would land troops from Brigadier General D.J.. Myer's 40th Infantry Division in the Uji Gunto and on the' islands of Kusakaki-shima, Kuro-shima, and Kuchino Erasu-shima, south of Kyushu. The seizure of these islands would clear the sea lanes to the west coast of Kyushu and provide sites for the early-warning radars and fighter-direction stations so essential to counter the expected heavy suicide plane attacks against the assault forces.4 In the Ryukyus campaign, the early occupation of the Kerama Retto in order to provide an emergency anchorage, had been one of~the decisive factors. A similar operation was included in the plan for OLYMPIC. On X-4 other elements of the 40th Division would seize the Koshiki _Retto west of Kyushu to establish an emergency anchorage and seaplane base. Also included with this operation was a contingency landing by the 158th RCT on Tanega-shima, south of Kyushu. This 83 landing would be conducted only if enemy forces on the island interfered with minesweeping operations in Osumi Strait. Otherwise, the 158th would reinforce the Kyushu landings after D+3.5 On X-Day (1 November), Turner would assume command of the main assault on Kyushu itself. Two corps of Sixth Army and the V MAC would land at three separate sites on the eastern and western coasts. The assault would be made in the standard "two up,one back" pattern used in previous amphibious assaults. Vice Admiral Daniel E. Barbey's Seventh Amphibious Force. would land troops from Major General I.P. Swift's I Corps- (25th, 33rd, and 4lst Infantry Divisions) on the beaches near Miyazaki. This force would seize airfields in the area and block any movement by enemy troops southward along the coast. The troops would move inland to the 0-1 line and southward to link up with XI Corps. The choice of this area for one of the main landings was a significant change from JWPC 235/3. While the authors of JWPC 235/3 recognized the importance of Miyazaki as a crucial transportation center between southern and northern Kyushu, in their opinions a main landing here was impractical, since it was too distant from the other landings to receive any support from them. The authors therefore chose Miyazaki as the objective for a possible secondary landing after D+15, in conjunction with an overland advance by the Eastern Force. In the case of OLYMPIC, however, the planners apparently though that a corps-sized 84 landing force could take care of itself. Vice Admiral Theodore S. Wilkinson's Third Amphibious Force would land Lieutenant General C.P. Hall's XI Corps (lst Cavalry, 43rd Infantry, and Americal Divisions) at the head of Ariake Bay south of Shibushi. After seizing the airfield near Shibushi, the troops would advance inland to the 0-1 line and link up with I Corps to the north. Once contact was established between the two corps, they would advance northward to the Final Beachhead Line. The sole assault on the western coast would be carried out by Vice Admiral Harry W. Hill's Fifth Amphibious Force' and Major General's Harry Schmidt's V MAC (2nd, 3rd, and 5th- Marine Divisions), which would land on the coast south of Kushikino. This force would seize the port of Kagoshima and prevent any enemy movement along the coast. After reaching the 0-1 line, the Marines would advance northward to the Final Beachhead Line. OLYMPIC also included the provision for a delayed landing by Major General C.W. Rider's IX Corps (77th, Blst, and 98th Infantry Divisions). After making a feint towards Shikoku around X-2 in the hope of diverting enemy attention from the main assault, the troops would proceed to the invasion area, arriving around X+3. The plan for employment of these troops was flexible, depending upon the tactical situation. Under it, Rear Admiral Bertram J. Rodgers' Reserve Force would land the Blst Division and corps troops on the southern coast in the vicinity of Makurasaki. The 85 98th Division might either land with the 8lst or be used to reinforce one of the other beachheads. The 77th Division would arrive after X+5 and would land where needed. The mission of IX Corps was to clear the southwestern shore of Kagoshima Bay and begin construction of airfields and other installations. Once the bay was secured, Rodgers would oversee the construction of an advance Naval Operating Base (NOB).6 The delayed landing by IX Corps was another difference between the OLYMPIC plan and JWPC 235/3. Under the latter, one division would land in the area on X-Day in order to open- Kagoshima Bay to the Navy as soon as possible. While' Kagoshima Bay was still an important objective for OLYMPIC, the early seizure of it was not as crucial as it had been in JWPC 235/3. The reason for this was the prior seizure of the Koshiki Retto as an emergency anchorage. Once all American troops had reached their Phase II lines, they would commence the third, or Consolidation, phase of the invasion. They would advance northward, destroying any remaining Japanese resistance. At the same time engineer forces from the various services would begin work on airfields, port facilities, and other installations needed to support the planned invasion of the Tokyo Plain. The Final Beachhead Line would cut diagonally across the island from Sendai in the west to Tsuno in the east. This was another difference from JWPC 235/3, which envisioned a line running from Sendai to either Miyazaki or Aburatsu. It is not clear JSashlkI \\® Hlloyolhl E107 fig? Sandal ‘ O- KOSHIKI \ 1 \ RETTO ES” \\ \ 0-4 XX E40 98 D -5 OKnnoyama . a sumo 0 E98 I: C) KURO-SHIMA K " X o E69 III ‘.,..4V 158‘ KUCHINO (I [Z 0-5 © AIRFIELD ERABU-SHIMA YAKU-SHIMA MRAILROAD ———MAIN ROAD EMINEFIELD 5 SUICIDE CRAFT BASE D-5 TANEGA-SHIMA MAP 3. PLAN FOR THE INVASION OF SOUTHERN KYUSHU(OPERATION “OLYMPIC”) I____._____—__| m Ki 87 why the plan was changed, but there are at least two possible reasons. One was to gain control of more airfields and airfield sites. There were four airfields in the new area, the existence of which was apparently unknown to the authors of JWPC 235/3. In addition to these airfields, the coastal plain north of Miyazaki Offered potential sites for the construction of new airfields. The second possible reason for the change was to deny the enemy any possible staging areas in southern Kyushu from which to launch a major counterattack. The new beachhead line 'would more closely follow the course of the Sammyaku range, forcing the Japanese- into the northern part of the island. Once the final beachhead line was reached, the Americans could begin to exploit their lodgment on Kyushu. Fighter-bombers would be within range of Tokyo and other targets in the industrial heartland of Japan, and could carry out large-scale attacks against these targets as preparation for the scheduled invasion of the Tokyo Plain in March 1946. Construction of bases and other installations would proceed, and supplies would be stockpiled. The invasion troops would remain on the island and prepare to carry out "such additional overland and amphibious operations on Kyushu and in the Inland Sea as may be directed subsequently."7 An integral part of OLYMPIC was a cover and deception plan, code-named PASTEL. PASTEL was originally drafted by Nimitz's and MacArthur's staff and submitted to Marshall and King for approval. The CCS had earlier issued a directive, 88 CCS 284/16/D, which set forth the objectives and means of implementation for all deception plans. PASTEL, however, had been drafted before the theater commanders received the directive, so during the week of 25 June 1945 Army and Navy officers from Nimitz's staff met with members of Joint Security Control (JSC) in Washington and revised PASTEL so that it met the criteria set down in CCS 284/16/D. In early July the JPS submitted a report to the JCS, JCS 1410, which presented the revision of PASTEL.8 The objective of PASTEL was to reduce enemy strength in the invasion area by misleading the Japanese regarding- American intentions and capabilities. The JPS listed a' number of factors that might influence Japanese estimates of the strategic situation. The Japanese were faced with the prospect of invasions of the homeland and the occupied areas of the Asian mainland; the problem of maintaining LOCs between Japan and the continent; the continued reduction of their air and naval forces; and the possibility of Soviet entry into the war. The Japanese had available the option of transferring their industry and goverment to the mainland if the homeland became untenable.9 The Japanese also had to consider American capabilities and intentions. American air and naval superiority interfered with the movement of Japanese forces by land and sea routes. American offensive strength, augmented by the arrival of forces from Europe, made possible simultaneous assaults at two or more widely separated locations. One 89 possible area for an assault was a location on the Asian mainland. From such a position the Americans could interdict Japanese LOCs across the Yellow Sea and the Sea of Japan and attack the Japanese homeland. They could also fix, engage, destroy major enemy forces on the, provide token support for a Soviet invasion of Manchuria, open a supply route to Chinese forces, and prevent the transfer of Japanese industry and government to the mainland. The planners used these factors as the basis for a ficticious assault on the Chusan-Shanghai area, with landings between August 1945 and March 1946 .'° The planners believed that around X-30 the possibility' of an assault on the homeland would become apparent to the Japanese, with the location of the assault area for OLYMPIC becoming apparent around X-lO. The Japanese could not rule out, however, the possibility of landings elsewhere in the Home Islands. One potential target was 'Shikoku, for it offered suitable landing beaches and airfields from which to attack military and industrial targets elsewhere in Japan. The most favorable period for a landing would be between November and February. The planners thus selected Shikoku as the target for another ficticious assault designed to support OLYMPIC." The feigned assault on the Chusan-Shanghai area was slated to occur first, with a target date in early September 1945. A cover story would be deliberately leaked to the Japanese that the casualties from the Okinawa campaign, the 90 need to release long-service veterans from the Pacific, and delays in the tranfer of forces from Europe meant that an invasion of Japan could not be conducted until the fall of 1946. In order to obtain positions from which to increase the air bombardment of Japan, to tighten the air and naval blockade of the homeland, and to support Chinese forces, a lodgment would be obtained in the Chusan-Shanghai area, to be followed by an advance into the Yellow Sea. The invasion would employ sixteen divisions, with a target date of 1 October 1945. In addition to this, forces would be built up in the Aleutians for ficticious landings in the Kuriles in 1945 and on Hokkaido in 1946, which would place American_ forces in a position to support the Soviets if they entered the war.12 There would be a shift in American strategy in early September. Another cover story would be created, stating that the deterioration of the Japanese position in China, the success of the bombardment of Japan, and the unexpected speed in the transfer of forces from Europe had brought about a change in plans. Eight divisions would be diverted from operations on the Asian mainland and used for an assault against Shikoku in late December 1945. This would give the § Americans additional bases from which to intensify the blockade and bombardment of Japan."3 A variety of means would have been used to implement the strategic deception measures outlined in PASTEL. Some of the forces assigned to OLYMPIC would conduct deception operations 91 both prior to and during the assault. Examples of these operations include the air strikes by FEAF against the Chusan-Ningpo area and the feint by IX Corps towards Shikoku during the early phases of the assault on Kyushu. Other forces not slated for OLYMPIC would also conduct deception operations against cover targets, provided they did not divert resources from more essential operations. Lastly, communications, intelligence, and psychological warfare channels would be used to spread false information to the Japanese.‘4 Because of the wide scope of deception measures outlined- in PASTEL, a number of organizations would be involved in its' execution. The JPS recommended a conference between CINCAFPAC; CINCPAC; CG, 20th Air Force; CG, U.S. Forces China Theater; CG, Alaskan Department; and Joint Security Control to work out details regarding the responsibility for the timing of the deception measures. CINCAFPAC would coordinate all detailed planning by his forces, as well as those belonging to CINCPAC, CG 20th Air Force, and COMGENCHINA, while Joint Security Control would be responsible for overall coordination and implementation of PASTEL.‘s It is difficult to determine how much of a contribution the cover and deception measures outlined in PASTEL would have made to the success of OLYMPIC, though one suspects they would have had only a limited effect. In choosing the Chusan-Shanghai area and Shikoku as targets, the JPS accurately assessed the Japanese view of American strategy. 92 The Japanese believed that, following the seizure of the Ryukyus, the Americans would seize bases in China and Korea to intensify the blockade and bombardment of Japan. As for potential targets for the initial assault on the homeland, the Japanese gave Kyushu the highest priority for defensive preparations, although they did not rule out the possibility of landings on Shikoku.‘6 Because the Japanese gave top priority to the defense of Kyushu, it is unlikely that the threat of attack against the Chusan-Shanghai area or Shikoku would have affected dispositions on Kyushu. The JPS hoped that the threat of~ landings in China would force the enemy to retain troops on’ the mainland that might otherwise be transferred back to Japan, but in a way the matter was academic. The Japanese were desperately short of shipping and had great difficulty maintaining communications with the mainland, and three or four divisions might have transferred from the mainland to Japan before OLYMPIC. The Chusan-Shanghai operation might have assisted the Chinese and Soviets if the threat forced the Japanese to transfer troops from Manchuria and South China. It is also unlikely that the invasion threat against Shikoku would have forced a major redeployment of Japanese forces from Kyushu. Any buildup on Shikoku would probably have been the result of the raising of units locally or the transfer of forces from elsewhere in Japan. Because of the need to defend Kyushu, the Tokyo Plain, and to ward off a 93 possible landing-on Hokkaido, any troop transfers to Shikoku probably would have come from the Osaka-Kobe-Kyoto area, since the defense of the two areas was the responsibility of the 15th Area Army. Given Shikoku's size and terrain, perhaps a maximum of five or six divisions would have been deployed there. Some aircraft might be transferred from Kyushu, but even so they would still be within range of the invasion area to conduct attacks against the invasion forces, or could have been redeployed within a few days. Because Kyushu was so vital to the Japanese, the American planners expected formidable resistance. 'One of ther- last intelligence estimates prepared by the Joint' Intelligence Committee (JIC) before the end of the war, JIC 311, examined defensive preparations in Japan. Among the preparations were the expansion of the army, the conservation of aircraft, the construction of new bases and the deployment of units to defend the most likely invasion areas, increased defensive mining, the construction of suicide boats and submarines, and emphasis on coordinated tactics between ground, air, and naval forces. The JIC estimated that the Japanese gave preparations in southern Kyushu the highest priority, since it appeared to be the most likely target for the initial assault on the homeland. Other possible target areas, in descending order, were Shikoku, northern Kyushu, and the Kanto Plain.‘7 Defensive preparations had accelerated greatly because of the perceived threat to southern Kyushu. For example, in 94 HOKKAHX) ’ C SAPPORO 51h AREA ARMY V MURORA 5 Infantry Dlvlslons 2 Intanlry Brigades fl KODATE 1m. AREA ARMY . 6 Infantry Dlvlslons 4 “ 2 Infantry BrIgado: HONSHU 15lh AREA ARMY 9 Infantry Division: 4 "Manny BrIgados KYOTO. KOBE ' Q 12:» AREA m V E 18 Infantry Dlvlllons rmrodDIvIslons { 7 Inlantry Brlgusos ° 0 3 Armored BrIgodos ~— . 3 ImporIal Guards BrIgzdos W! S H IKO KU 3:22:31 335:2: '° NAGASAKI g? 0 1 Armor-d Bilgodq KAGOSHI'LA KYUSHU 16". AREA ARMY . 14 Intantry Diviséoru " O Tlnlanlry Brigades 3Armorod Br Igzdes MAP 4. JAPANESE TROOP DISPOSITIONS, AUGUST 1945 am th P8 in 0f as: 95 early 1945 the ground forces on Kyushu consisted of just one active and two depot divisions, plus army troops, for a total of some 150,000 men. As of late July, there were eleven active and two depot divisions, plus army troops, for a total of some 545,000 men. Two divisions had been transferred to Kyushu from Manchuria, two from Honshu, one from Hokkaido, and one from an unknown location in Japan. Four more active divisions had been raised locally from depot divisions. In addition to these troops, there were also three armored brigades and an independent mixed brigade, as well as an amphibious brigade that had been recently transferred from' the Kuriles. The deployment of these forces reflected the. perceived threat to southern Kyushu. In early 1945, 75 percent of the troops on Kyushu were deployed in the northern part of the island. By late July, 60 percent of the troops, including seven of the eleven active divisions, were located in southern Kyushu.‘8 The deployment of suicide aircraft was also indicative of the likelihood that southern Kyushu was the target for assault. According to the JIC, some fifty bases for suicide aircraft had been built in Kyushu, Shikoku, and Honshu west of 133 degrees east longitude. The Japanese navy had also deployed some 1,200 biplane trainers in these areas. Since these slow aircraft would be easy targets for a warship's guns, they would have been primarily used against the less heavily-armed transports and landing craft. The size of the threat can be judged in comparison with the deployment of 96 suicide aircraft elsewhere in Japan. East of 133 degrees east longitude, an area that included the Tokyo Plain, there were fifty-four bases and some 1,400 trainers.‘9 Carrier strikes against Japanese naval bases in July destroyed most of the Imperial Navy's few remaining capital ships. With these vessels out of action, some 100,000 naval personnel were available for other duties, especially defensive preparations on Kyushu and nearby areas. Some personnel were formed into special naval landing forces (the Japanese version of the Marines) in order to support the Army in the defense of Kyushu. Other personnel were formed intor' special suicide attack units, and manned midget submarineS' (KAIRYU and KORYU), suicide boats (SHINYO), and human torpedoes (KAITEN). Others were formed into underwater swimming teams, which would attach limpet mines to American ships. Additionally, the few remaining destroyers and submarines of the Imperial Navy would make suicide attacks against the landings.20 While all of these measures added up to formidable defenses on Kyushu, perhaps none were so feared as suicide aircraft, or Kamikazes. An assessment of the capabilities of the Japanese air forces, JIC 307, was prepared in mid-July. The JIC estimated total Japanese air strength at 5,000 combat and 6,000 trainer aircraft. In response to OLYMPIC, the JIC estimated that 4,000 combat and 5,000 trainer aircraft would be employed. The JIC stated that, in its opinion, the 'Japanese would "commit all available combat and trainer type 97 aircraft against our invasion forces, primarily in suicide attacks, and without regard to the conservation of air strength for a later defense of other areas." It estimated that the Japanese would be able to dispatch 600 sorties by combat aircraft and monoplane trainers and 300 sorties by biplane trainers during a given 24-hour period. With their resources, the Japanese could sustain such a rate for only a short time, after which attacks would diminish until all aircraft were expended.21 Given the size of the opposing forces and the stakes involved, there is little doubt that the invasion of Kyushur- would have been the costliest campaign in the Pacific up to that time. In order to find anything comparable in terms of size and fury, one would have to look to some of the savage battles between the Soviets and Germans on the Eastern Front. The American assault troops had a great superiority in firepower and perhaps a slight superiority in manpower, and thus probably could have established a lodgment on Kyushu. The problem would have been trying to expand the size of the lodgment, for the Japanese troops were well-deployed to contain the American forces. The landing by I Corps at Miyazaki would have encountered the stiffest opposition. There were three enemy divisions and an armored brigade near the landing site: the 156th Infantry Division and 5th Tank Brigade at Honjo, the 154th Infantry Division at Tsuma, and the 212th Infantry Division at Tsuno. Another division and another armored brigade were stationed further inland and 98 could have moved into the battle area on short order. These units, the 25th Infantry Division and the 6th Tank Brigade, were located at Kobayashi and Kirishima, respectively.22 The western landing by V MAC would have also met strong opposition. Two enemy divisions were located in the immediate assault area: the 146th Infantry at Kawanabe and the 206th Infantry at Izaku. Two other divisions and an independent mixed brigade were stationed nearby and could have reinforced the assault area: the 303rd Infantry Division at Sendai, the 77th Infantry Division at Kajiki, and the 125th Brigade at Ibusuki. The 125th might have been held" back, however, in order to counter any landings on the south' coast.23 Of the main landings, the one by XI Corps at Ariake Bay would have encountered the least opposition. Just a single division and an indepedent mixed brigade were located near the assault area: the 86th Infantry Division at Shibushi and the 98th Brigade at Kaneyama. The offshore landings would have encountered moderate resistance. The 40th Infantry Division would have faced an independent mixed brigade, the 107th, in the Koshiki Retto and smaller units on the other islands. The 158th RCT would have encountered an independent mixed brigade, the 109th, if it became necessary to land on Tanega-shima.2‘ The Japanese had five infantry divisions, three independent mixed brigades, and an armored brigade located in Kyushu and adjacent islands, which could have moved to 99 southern Kyushu within two weeks after the assault. American air attacks against the road and rail lines between northern and southern Kyushu would have made it extremely difficult for the Japanese to move large forces into the invasion area}5 The Americans would have encountered considerable difficulty in obtaining reinforcements. Two divisions of IX Corps, the 77th and Blst Infantry, would have been available to reinforce any of the beachheads after X+5 (6 November). Sixth Army reserve, the 11th Airborne Division, was not scheduled to arrive until X+22 (23 November), but the schedule might have been advanced considerably because of”. heavy enemy resistance. If these troops were not enough, units of the Eighth Army, staging in the Philippines for the invasion of the Tokyo Plain, might have been drawn upon, which would have probably delayed that landing by several weeks. The American forces were bedeviled by other problems that would have had an effect on OLYMPIC. One was the state of the troops themselves. Almost all of the divisions slated for the operation had been overseas nearly two years, and many officers and men had been in the Pacific for three years. Many‘were exhausted by their campaigns and should have begn sent home, but there were few replacements available (the problem of replacements was discussed earlier). The shortage of infantrymen was particularly acute, and during the Okinawa campaign some Army divisions were short some 1,000 infantrymen.26 100 Another problem was the timing of OLYMPIC as related to previous operations. With two exceptions, all of the divisions slated for OLYMPIC had been engaged in severe fighting earlier in 1945. Eight divisions had participated in the liberation of the Philippines: 25th Infantry, 33rd Infantry, 40th Infantry, 4lst Infantry, 43rd Infantry, Americal, lst Cavalry, and 11th Airborne. Elements of the 40th Infantry, 11th Airborne, and Americal divisions were engaged in mopping-up operations as late as mid-August. As for the other divisions, the 3rd and 5th Marines had fought at Iwo Jima and the 2nd at Okinawa. Only the Blst Infantry/T which had fought in the Palaus campaign in the fall of 1944,‘ and the 98th Infantry, which had not yet received its baptism of fire, had no recent campaigns to their credit!7 All of the units engaged in the earlier fighting needed time to relax, replace casualties, and gear up for OLYMPIC. There was, however, simply not enough time available. The 1 November target date was the latest possible for an invasion in 1945. Deteriorating weather conditions, particularly the height of the typhoon season, would have delayed the invasion until the spring of 1946, which would have also meant a delay in the invasion of the Tokyo Plain. In fact, if the war had continued, OLYMPIC probably would have been delayed, for in early October a devastating typhoon hit the Ryukyus, destroying many of the landing craft meant for the invasion as well as airfields and other facilities. The losses were too great to recover from before the beginning of November. 101 The Japanese would have considered the typhoon another "divine wind", just like the one that saved them from a Mongol invasion in 1281.28 The delay in launching OLYMPIC would have given the advocates of defeating Japan through blockade and bombardment more time to prove the validity of their position. In order to Obtain bases from which to intensify the bombardment and blockade, it is possible that landings in the vicinity of Shanghai, code-named LONGTOM, might have been carried out in October or November 1945. Such an operation no doubt would have received considerable opposition from proponents of an" invasion of Japan, for in their Opinions it would have- consumed resources that should have been conserved and contribute little to the defeat of the Japanese army in the Home Islands. In a way the matter is academic, however, since Japanese officials interrogated after the end of the war stated that "Japan would have surrendered to the air attack (by 1 November some said) even if no surface invasion had been planned, if Russia had not entered the war, and if the atomic bombs had not been dropped."29 CHAPTER 8 NORTHERN HONSHU Both the Americans and the Japanese made massive preparations for a decisive battle on Kyushu. Nevertheless, it is quite possible that the battle would have never occurred, for on 9 August (the day an atomic bomb was dropped on Nagasaki), the JWPC submitted a plan to the JCS that outlined a major shift in American strategy. This plan, JWPC 398/1, called for the seizure of northern Honshu as an alternative to southern Kyushu, offering the explanation that the recent large enemy build-up on Kyushu made it a much less attractive target.‘ The strategic significance of northern Honshu had been I noticed by the JWPC earlier in the summer of 1945. On 26 July they submitted a plan, JWPC 333/1, to the JPS for consideration. JWPC 333/1 outlined a number of possible operations that might have to be carried out if the Japanese 2 One of did not surrender after the loss of the Tokyo Plain. the targets was the Tsugaru Strait, which separates Honshu and Hokkaido. The original plan called for a series of landings on both shores of the strait in order to isolate Hokkaido from the rest of Japan, as well as to open a route to the Sea Of Japan and the Soviet Far East. The plan was modified in JWPC 398/1, which outlined a plan for the seizure of only northern Honshu, from which the Americans could support the invasion of the Tokyo Plain. The most prominent geographic feature of northern Honshu 102 103 is the fine anchorage of Mutsu Bay, which is separated from the Pacific and Tsugaru Strait by the Shimokita Peninsula and from the Sea of Japan by the Tsugaru Peninsula. There are two plains on each coast, the Hachinohe Lowland between Noheji and Hachinohe on the east coast, and the Tsugaru Lowland between Hirosaki and Jusan on the west. With the exception of a small plain near Aomori, the rest of the terrain consists of rugged mountains. Northern Honshu was a good position from which to support the invasion of the Tokyo Plain. Mutsu Bay was a fine anchorage for an advance Naval Operating Base, and there” were five airfields and two landing strips in the area, as} well as sites for fifteen other airfields. The sites were graded by the amount of engineering effort needed to develop them: four good, seven fair, and four poor. All told, this offered the basing potential for some 1,300 aircraft. The distance to Tokyo was approximately 400 miles, while the distance from southern Kyushu to Tokyo was approximately 600 miles.3 From a tactical standpoint, northern Honshu offered a number of advantages. The area was lightly defended and, because of the mountain barriers to the south, difficult for the enemy to reinforce. An assault in this area would require a major shift in Japanese defensive dispositions, reduce the rate of enemy reinforcement, and, on a possibly larger scale, create such confusion and disorder as to make subsequent American landings easier. There were many good landing 104 beaches, which would force the Japanese to spread their resources thinly. Lastly, an assault would open Tsugaru Strait, which would provide access to the Sea of Japan and open up new areas for potential assaults. Among the disadvantages was the distance of the target area from the nearest American bases (more than 1,200 miles from Okinawa, for example), which would severely limit the amount of land-based air support available. Since the area was lightly defended, there would be no opportunity to fix, engage, and destroy major enemy forces. If northern Honshu was selected over Kyushu, it would have meant a massive reorientation of' American effort on very short notice. Lastly, military. operations in the area would have been adversely affected by the harsh winters.4 The objective of the invasion of northern Honshu was to destroy enemy forces and gain positions from which to increase the blockade and bombing of Japan and to support the invasion of the Tokyo Plain. To carry out the invasion, the planners proposed the use of many of the forces allocated to OLYMPIC. Twelve divisions would have been employed, ten in the initial assault and two in reserve. Air support would have been furnished primarily by carrier-based aircraft, with B-29's also being employed to some extent. Allied air forces based in the Ryukyus would conduct air strikes against targets on Kyushu, Shikoku, and Honshu in order to tie down enemy airpower away from the assault area and to disrupt lines of communication in central Honshu. The target date 105 for the assault was 15 October. Timing was especially crucial, since the planners estimated that fifty-five days would be required to get all of the airfields and potential sites into operation. All work would have had to be completed by 15 December, after which frozen ground would virtually shut down all construction activity until spring.‘5 Preliminary operations in the assault area would commence as soon as posssible, on an intermittent basis. Naval forces would attack key targets and discreetly carry out photographic and visual reconnaisance of the target area. These attacks would be conducted in such a way so as not to?- arouse enemy suspicions about a possible assault. U.S. Navy, forces had already carried out attacks against northern Honshu and southern Hokkaido during July, so their reappearance in the area would have been nothing new. Shortly before D-Day the main attack forces would arrive in the assault area to conduct pre-invasion shore bombardment and minesweeping. On D-Day landings would take place on the eastern and northern coasts. One corps of three divisions would land near Hachinohe, seize the small port of Minato and the airfield at Hachinohe. After occupying these objectives, these troops would have advanced on Sannohe and established a lodgment along the 0-1 line. After reaching the line, the corps would block enemy troop movements from the south.6 Just north of Hachinohe a corps of two divisions would land between Futakawame and Misawa. Its mission was to seize 106 the airfield at Misawa and the airfield sites at Momoishi, Shichinohe, and Sambongi. After establishing a lodgment along the 0-1 line, these troops would advance overland to seize Noheji. A third corps, consisting of three divisions, would land on the north shore of the Shimokita Peninsula east of Ohata, initially seizing the airfields and airfields sites within the 0-1 zone, and then occupy Ominato and the rest of the peninsula. These troops would then advance down the neck of the Shimokita Peninsula to link up with the other American forces. On D-Day some units of this corps would land on both' sides of Oma-saki to destroy the coast defenses that.‘ controlled the eastern entrance to Tsugaru Strait. On D+l minesweepers would clear channels in Tsugaru and Tariadate Straits, and on D+2 a regimental combat team would have landed on both sides of Tariadate Strait to destroy coast defenses.7 On D+3 minesweepers would clear a channel through Tariadate Strait and begin work in Mutsu Bay. On D+4 a bombardment group would enter the bay, and on D+5 a corps of two divisions would land east of Aomori. This corps would destroy enemy forces in the area, seize the airfield near Aomori, and establish contact with the troops that conducted the east coast landings. Afterwards, these troops would occupy Hirosaki and gain control of the mountain passes between Ajigasawa and Lake Towada in order to interdict the movement of enemy troops from the south. 107 As soon as forces were available, troops would land on both sides of Tappi-saki to complete the destruction of enemy coastal defenses along Tsugaru Strait, allowing minesweepers to complete their clearance of the strait. The remaining forces would clear any remaining enemy troops from the area contained within the final beachhead line, which ran from just west of Ajigasawa, along the northern shore of Lake Towada, and to the Pacific from Sannohe. Once the beachhead was secured, five divisions would remain behind to serve as a garrison while the rest of the troops would be withdrawn for possible employment elsewhere.8 A» According to the latest intelligence estimates by the- JIC, enemy opposition to an assault on northern Honshu would be considerably less than on Kyushu. In northern Honshu there were two active and one depot division, plus army troops, for a total of some 100,000 men. There were also large numbers of civilians available for supplemental military duties. One division defended the Tsugaru Lowland and the northern parts of the Central Range, while the other division defended the Shimokita Peninsula and Hachinohe Lowlands.9 The JIC estimated that the landings would initially be met with light enemy opposition, though within 48 hours the enemy would commit all available troops in the area to battle. Enemy reinforcments would begin to move up from the south as soon as the Japanese high command realized that the assault was a major attack and not simply a diversion. The 108 Japanese would have faced considerable difficulties in reinforcing the assault area. The nearest sizeable troop reserve was located near the Tokyo Plain, some 400 miles to the south. The transportation system was inadequate for large troop movements, and its effectiveness would have been further reduced by heavy American air strikes. The JIC estimated the Japanese might employ at most five divisions to Oppose the assault.‘0 The JIC also estimated that enemy air forces would offer only moderate opposition to the landings at first. There were some 300 combat aircraft and a somewhat larger number of, biplane trainers based in northern Honshu and southern. Hokkaido. During the first days of the assault the Japanese might carry out perhaps some 200 sorties by combat aircraft and 50-100 sorties by trainers during a 24-hour period. Neutralization of enemy airfields by American air strikes, however, might result in a reduction in the number of sorties. The movement of enemy air reinforcements into the invasion area depended upon Japanese assessment of the purpose of the invasion. If they saw the assault as a diversion Or with a limited Objective, the Japanese probably would have withheld their main air strength for use against landings in more vital areas of Japan, such as the Tokyo Plain. Otherwise, the JIC estimated a maximum air effort by the Japanese against the invasion, with up to 400 sorties by combat aircraft and 100-200 sorties by trainers during a 109 WRAILROAD MAIN ROAD 6) AIRFIELD ‘UUIUO O LANDING GROUND a“ xxx D GOOD sure i 50 c A OMA—SAKI H [I FAIR SITE /3DIVS D DAY I POOR SITE I I I Ohata ON ORDER D + 2 ‘ l l I 0—1 ‘ \‘ [j TAPPI— ~~ z] SAKI Lu ‘2) O . o x a Q OmInan . ~-~ q \ tr <1 Sambongi fl Fukaura r . . I ? Momoishi HIrosakI XXX 0 SDIVS <37 I O I . 4:9 I Gonohe Hachinohe 6;, I 0 LI LAKE \ NE TOWADA ’ \ 0_1 ,” , ,..... Saknohe ,” ‘_ -II-‘ Ono Hachimori MAP 5. PLAN FOR THE INVASION OF NORTHERN HONSHU (JWPC 398/1) llO 24-hour period after D+5.11 The JIC expected minimal naval opposition to the invasion. A few destroyers might attempt to attack the landings, but given overwhelming American naval superiority, they would have been disposed of quickly. Japanese submarines were judged to be ineffective, and suicide craft were considered to be little more than nuisances. Extensive minefields along the coast and in Tsugaru Strait posed the greatest naval obstacle to an invasion.‘2 In many ways the plan for the invasion of northern Honshu made much more sense than the OLYMPIC plan. It' allowed American forces to obtain a foothold in Japan at a A much lower cost than OLYMPIC. It was consistent with American strategy throughout much of the war, in that it bypassed a point of enemy strength in favor of a less-heavily defended target that Offered many of the same advantages. The plan did introduce a number of new problems. First, there was the matter of reorienting Allied planning and preparations to the new plan, on very short notice. Second, there would be the problem of acclimatizing troops that had fought in the tropics to a winter campaign. Along with this was the logistical problem of obtaining suitable winter equipment for the troops. None of these problems were insurmountable, though they would have tested American versatility and adaptability. CHAPTER 9 "CORONET" The importance of the Tokyo region to the Japanese war effort had been recognized as early as July 1943, in JWPC 46/5. Because of this, the Tokyo (Kanto) Plain was considered the ultimate obective of any invasion of Japan. The Allies hoped that occupation of the area would force the Japanese into an unconditional surrender. During early 1945 the JWPC worked on a plan for an assault on the Kanto Plain. Its work resulted in the submission of a plan, JWPC 263/4, to the JPS some three weeks before the issuance of the directive for Operation OLYMPIC.’ The plan envisioned two possible scenarios: an assault within three months after the invasion of Kyushu, or, in the event that Kyushu was bypassed, as early as January 1946. The first scenario depended upon the use of troops deployed from Europe, while the second would use only troops already in the Pacific theatre.1 The overall objective of the operation, later given the code-name CORONET, was to inflict a decisive defeat on the Japanese Army in the heart of the Empire and force an unconditional surrender. If the Japanese did not surrender, then the Allies would have gained positions from which to conduct further operations against the remaining Japanese forces in the Home Islands. The plan called for the employment of twenty-three divisions (including five armored), with simultaneous assault lift for fourteen 111 112 divisions; more than 3,500 warships, ranging from aircraft carriers to landing craft; and some 7,000 land- and carrier-based aircraft.2 The Tokyo Plain is the largest in Japan, covering some 5,000 to 6,000 square miles. It is bounded by mountains on the north and west and by the Pacific on the south and east. Tokyo Bay is located in the southern part of the plain, and is connected to the Pacific by Uraga Strait. The largest urban area of Japan, consisting of Tokyo, Kawasaki, Yokohama, and Yokosuka, is located along the western shore of the bay. From a military standpoint, the region was a very attractive' target. There were a number of suitable landing beaches; there was sufficient maneuver area for the Americans to exploit fully their advantage in mechanized forces; the area was the seat of government and communication center for the Home Islands; it offered the best port facilities in Japan; and it contained half of Japan's defense industry.3 Given the size of the invasion, it was imperative that suitable port facilities be seized and developed as soon as possible in order to support the forces ashore, since adverse surf conditions would hinder supply across the landing beaches. The opening of Urage Strait and the early seizure of the Yokohama-Yokosuka port complex, therefore, were the prime targets of the assault. Since the opening of Uraga Strait would require control of both shores, at least two separate landings would be necessary, the planners recommended landings at two or more points, with the main 113 effort at one. Such an approach would force the dispersal of enemy forces to cover all possible landing areas, make effective use of the element of suprise, and be flexible enough to meet changing tactical conditions. Four possible options were considered for the main landings and route of advance to Tokyo: south of Isohama and along Route 1, near Choshi and along Route 2, near Katakai and along Route 3, and in the Oiso-Katase area at the head of Sagami Bay and along Route 4.4 Among the advantage of the landing south of Isohama were the existence of little rice land and a number of roads and' railroads. There were three airfields within ten miles of the beaches. Ground opposition would probably be light, perhaps no more than one division plus local reservists. There were, however, far more disadvantages. The beaches were for the most part flat, with a gradient of 1:150. Supplies would have to move across open beaches, exposed to winds and heavy surf. Immediately behind the beaches were bluffs 100-200 feet in height, while further inland the Abukuma highlands and the rice terraces offered good defensive positions for the enemy, which would require considerable time and effort to clear. There were two defiles of four and eleven miles, as well as two unfordable rivers. There were no key objectives in the area, and it was unlikely that any major enemy forces would be destroyed. Lastly, this operation would not significantly aid in the early seizure of Yokohama-Yokosuka.5 114 The second course, the main effort near Choshi, had a few advantages. There were long landing beaches, with generally level ground behind them. There were five airfields within twenty miles of Choshi, while the port of Choshi could be opened as a supply base early in the campaign. The disadvantages were largely geographic. As at Isohama, the beaches had a flat gradient and were subjected to winds and heavy surf. A large part of the area was rice land which, together with several river basins, would impede troops movements. From a tactical standpoint, it was unlikely that operations in this area would fix and destroys” large numbers of enemy troops. Supplies would have to move 0 across the beaches and, later, through a small port, with the potential for creating a logistical bottleneck that could damage the entire campaign. Lastly, these landings would not contribute greatly to the early seizure of Yokohama-Yokosuka,.6 The third course, the main effort at Katakai, had almost equal numbers of advantages and disadvantages. As for the advantages, the Chiba Peninsula could be isolated after an overland advance of only eighteen miles, thereby making it possible to eliminate enemy coast defenses along the eastern shore of Uraga Strait and Tokyo Bay. There were five airfields located within twelve miles of Katakai, and there was a good network of secondary roads in the area. The terrain was generally well-suited for military operations, especially during the dry-paddy period from November to March. The beaches suffered from the same problems of 115 Koga / CD ~ * «4 M Kumagaya 'ShIOKa Hokola ‘ 1~ T Iura V ID 8 Chicthu Noda YaIabe 4? Omiya Kawago 1 Urawa ‘<‘ B ’ Ome Kawaguchi 5’ b Choshi Ichikawa/ Tachikawa Funa ashi .Hachioji 0Q} @ .{l TOKYO Chiba 050 {— TOKYO WAN Katakai KAWASAKI Anegasaki © Atsugi YOKOHAMA Mobara Ch sak HIratsuka Kamakura Fuiisawa GnM‘ . - Odawara SA ZushI Yokosuka Uraga . Ohara SAGAMI WAN G O Q \ Atami a? K a Mishima Y mogawa D (5 v (t D Matsuhara TaIeyama WRAILROAD _ROAD LANDING BEACH AA PHYSICAL RESTRICTION MAP 6. POSSIBLE INVASION ROUTES, KANTO (TOKYO) PLAIN (JWPC 263/4) la qc 81 mi I'C Yo La ma tr Wo- We: The aim 116 gradient and vulnerability to wind and surf as at Isohama and Choshi. There was a five-mile stretch of rice land directly behind the beaches, and access to the Kanto Plain itself was through a nine-mile wide corridor that would not doubt be heavily-defended. Lastly, there were no ports in the area, making it extremely difficult to resupply the troops ashore.7 The fourth course, with the main landings in the Oiso-Katase area at the head of Sagami Bay and secondary landings elsewhere, was the best overall choice. There were good landing beaches with deep approaches in a .sheltered area, while the terrain inland was suitable for large-scale' military operations. This approach also offered the shortest route to Tokyo as well as the clearance of the western shore of Uraga Strait and the early opening of the Yokohama-Yokosuka port complex and three nearby airfields. Landings in this area would also fix, engage, and destroy major enemy forces. A short advance would isolate enemy troops in the Yokosuka Peninsula, while other operations would interdict two primary lines of communication from the west, which would delay the arrival of enemy reinforcements. The landing areas and approaches contained the heaviest beach and coast defenses of the four sites, thereby increasing the cost of establishing a lodgment.a Based on their assessment of the advantages and disadvantages of these four options, the JWPC recommended that landings should be made on both the east coast and at Sagami Bay. The main landing would be in Sagami Bay near 117 Oiso-Katase, with the objective of early occupation of the Yokohama-Yokosuka port complex. Secondary landings would take place on the east coast near Katakai and Choshi, which would help open Uraga Strait and establish American airpower ashore as soon as possible.9 The plan consisted of six phases. During Phase I, which covered the period D-180 to D-Day, Allied forces would destroy enemy aircraft, coast defenses, and communications in the invasion area, with the effort becoming progressively heavier as D-Day approached. The defenses around Tokyo Bay were the strongest in Japan, and all would have .to be' eliminated or neutralized. A variety of weapons would have been employed, including bombs, rockets, naval bombardment, and chemical defoliants to remove vegetation cover. The pre-invasion bombardment would soften up not only the landing areas, but also the areas lying within 1,000 to 5,000 yards of the beaches, in order to eliminate staging areas for enemy reinforcements for the beaches.‘0 The first landings would occur on D-Day on the eastern coast of the plain. A corps of three infantry divisions would land near Katakai, to be followed by an armored division on 0+5 and two more infantry divisions on D+10 and D+25, respectively. After establishing a beachhead, these forces would advance to cut off the Chiba Peninsula, seize the four airfields near Katakai, and destroy enemy coastal batteries on the western shore of the peninsula. Also on D—Day, another two divisions would land at Ioka, 118 six miles southwest of Choshi. After seizing the airfield at Itono and the airfield and port of Choshi, these troops with link up with the Katakai force and proceed to eliminate enemy troops in the area. By D+40 both forces should have reached the 0-4 line. Around D+35 an armored division would land at Choshi, which would spearhead the advance from the 0-4 line.‘1 During Phase III a demonstration landing involving two divisions would take place near Kashima on D+7 and D+8, which would hopefully draw enemy reserves to the northeastern part of the plain. Normal pre-invasion operations, such as minesweeping and shore bombardment, would be carried out to- make the demonstration appear realistic, though no troops would land. Once the operation was completed, the two divisions would be employed in the main landing at Sagami Bay.12 Phase IV consisted of the main landing at Sagami Bay on D+10. A corps of three infantry divisions would land in the Kozu-Oiso-Katase area at the head of the bay. These troops would be followed on D+14 by a corps consisting of an armored idivision and an infantry division. The initial Objectives of this force were to secure the beachhead, to seize the Hatano-Matsuda line to interdict the movement of enemy reinforcements from the west; and to seize the Kanazawa-Uranogo line to isolate the Yokosuka Peninsula.‘3 Once the initial objectives had been achieved, more troops would land to continue the destruction of Japanese resistance in the area. On D+19 a third corps, consisting of KATAKAI FORCE D+5 [Ex] D+1o [i] Mg SAGAMI FORCE xx xx xx x , WEEE" x x w®@ x mgg r2 xx xx nacla D+2SIE IX] X xx xx ~‘\ I D+3°IXI E33 PHASE IV ‘. I, ’ ARMY GROUP RESERVE XX X PHASE I xx x Prollmlnary Operations E IE IE (9 G ' Koga (9 G N A Q G) W Mv .‘ K lshloka . .A Hokota 3‘" «JG . ' ' ‘ agaya - I” h RIM!“ DEMONSTRATION ‘. G. we iota .. XX XX XX WEEX X D+7D+8® JM—l; PHASE III ’ 0—3 , \ 0—2 ‘\ 0—1 ”Chou“ . CHOSHI FORCE /atakal D—DAYg 38? XX \ D+35 [Q 1 PHASEII WRAILROAD ROAD Q AIRFIELD MAP 7. PLAN FOR THE INVASION OF THE KANTO(TOKYOI PLAINIJWPC 263/4) 120 an armored division and an infantry division, would land to aid in the destruction of Japanese defenses in the Yokosuka Peninsula. This corps would land at either Sagami Bay or at Koto Bay on the west side of the peninsula, depending upon the tactical situation. On D+25 two divisions of a fourth corps would land to spearhead an advance towards the Tama River. Another infantry division and an armored division from this corps would land on D+30. Phase IV would end once the Yokosuka Peninsula and the area south of the Tama River were occupied. There were also contingency operations that might have been included in Phase IV. If air power was unable to interdict the main enemy reinforcement routes from I western Honshu, airborne troops might be employed to seize Hakone Pass and a pass near Yamakita. Hakone Pass could also be seized through an amphibious assault on the Izu PeninsulaJ‘ Phase V, which would have begun around D+40, called for coordinated action by all three invasion forces, with the objectives of destroying any remaining enemy forces in the plain and the seizure of all defiles leading into the plain. In the sixth, or Exploitation, phase, the invaders would consolidate their occupation of the plain, and, in the event that the Japanese did not surrender, prepare for further operations to bring about the defeat of the remaining Japanese forces in the Home Islands, including tightening the naval blockade and intensifying the air offensive against the remaining industrial and military targets.15 The planners estimated that six active divisions 121 (including an armored division), three depot divisions, plus army troops, totaling 300,000 men, would probably be deployed to defend the Kanto Plain. If Kyushu was bypassed, 35 divisions (including 10 depot divisions) would be available as reinforcements. If Kyushu was invaded first, then 27 divisions would be available. Because of the restricted size of the area,capacity of roads and railroads for troop movements, and the success of American air attacks against enemy lines of communications, the Japanese might be able to support ten or twelve divisions in the plain, the troops being committed piecemeal until all available forces were expended .15 During the months prior to the invasion, American airpower would ' have greatly reduced Japanese air capabilities. The JWPC estimated that some 2,000 combat aircraft would be available in Japan proper, with 1,300 of them on Honshu and Shikoku, close to the invasion areas. The Japanese would have used these aircraft, as well as those tranferred from other areas, in all-out suicide attacks against the invasion fleet, with no regard towards conservation of resources. Given attacks on such a scale, the JWPC estimated that enemy airpower would cease to be a factor after ten days. The Imperial Navy would have posed little more than a nuisance to the invasion. Any remaining surface ships would have been quickly disposed of, forcing the Japanese to rely on conventional and midget submarines as well as various 122 types of suicide craft. In the opinion of the JWPC, none of these forces should be regarded as a serious threat to the invasion.‘7 The invasion plan also included a number of cover and deception measures, which were outlined in JWPC 190/16. The purpose of these measures was to lessen enemy resistance in the invasion area by deceiving the enemy about actual American intentions and capabilities. JWPC 190/16 was based to a large extent on PASTEL (the cover and deception plan for OLYMPIC), and continued the ficticious threats against Shikoku and Hokkaido. JWPC 190/16 introduced a new target' for a ficticious assault: Pusan, Korea, around mid-April 1946 in order to isolate Japan from the Asian mainland. OLYMPIC itself would be justified to the Japanese under the cover and deception plan as a necessary step to eliminate suicide plane bases that might interfere with the ficticious assault on Shikoku.‘8 A number of methods would have been used to deceive the Japanese. Bombing and reconnaisance missions would be flown in increasing numbers over the ficticious target areas. Troops staging for CORONBT would be alerted that they were scheduled for assaults against other targets. If these plans were leaked to enemy agents, it would have been false information. Parachutes, rubber boats, and equipment would be left in the ficticious target areas, to mislead the Japanese to think that commando and scouting units had been there.‘9 123 \‘r l I \. '0 Senai SENDAI PLAIN 5 AIRFIELDS 6 POTENTIAL SITES \ 54$ Z O 0 sun“ ’ 1 AIRFIELD 2 9075mm. sures 0 NH mu 1 AIRFIELD 1 POTENTIAL sms HANAI‘ATSU w 2 AIRFIELDS 7 POTENTIAL SITES MIYAKE IAIRFIELD ° O O roxusmux rum ______’_____ 1 “anew 4 POTENTIAL SITES KOCHI PLAIN 2 AIRFIELDS I POTENTIAL SITE HACNIJO 1 AIRFIELD 1 POTENTIAL sue MAP 8. OPERATIONS PRECEDING “CORONET"(JWPC 359/1) 124 One of the reason for conducting the invasion of Kyushu was to gain airfields from which to support CORONET. Southern Kyushu was approximately 600 miles from Tokyo, and there was some concern whether fighters stationed there would have been able to support the invasion effectively. In June 1945 the JWPC prepared a report, JWPC 359/1, which examined the possibility of seizing areas closer to Tokyo for the purpose of obtaining better air support for the invasion. Eight possible sites were consideredzi the Sendai Plain and Hamamatsu Lowlands of Honshu, the Tokushima and Kochi plains of Shikoku, and four islands in the Izu Group, south of' Tokyo: O-shima, Miyake, Nii, and Hachijo. With the I exception of the two sites on Shikoku, all of the sites were within 300 miles of Tokyo. The Shikoku sites, which were within 400 miles of Tokyo, were listed because the surrounding hills would have made it easy to establish a defensive perimeter for a lodgment.2° After examining the merits of each site, the JWPC concluded that the benefits resulting from their seizure were more than outweighed by the risks involved. Since all were fairly close to Tokyo, any assault would have encountered fierce resistance, especially mass attacks by suicide planes. The possibility that the fleet would suffer extensive losses or damage might also delay the invasion of Tokyo. The troops involved in the operations would have been unavailable for CORONET, thus resulting in further delays. The JWPC concluded that proper coordination between Kyushu-based and 125 carrier-based fighters would be able to furnish the invasion with adequate air support.21 When the war ended the planning and preparations for CORONET were in the early stages. The assault forces, however, had been designated. For the most part, the overall assault plan was based on JWPC 263/4. A total of twenty-seven divisions were slated for the operation. General Robert L. Eichelberger's Eighth Army , consisting of X, XIII, and XIV Corp, would have made the landings at Sagami Bay. General Courtney H. Hodge's First Army, consisting of III Marine Amphibious and XXIV Corps would have made the east- coast landings. Many of the follow-up forces would have been. made up of troops redeployed from Europe.22 Unlike OLYMPIC, CORONET would have been an Allied operation, for the British would have furnished three to five Commonwealth divisions, to serve under American command.23 Nature would have aided the Japanese in resisting the invasion. OLYMPIC was plagued by a typhoon, while CORONET would have encountered heavy snowfalls during March.“4 The European veterans might have coped with the cold weather, but the other troops, veterans of tropical campaigns, would have had trouble} CHAPTER 10 NORTHWESTERN KYUSHU Although CORONET was scheduled for some four months after OLYMPIC, there was the possibility that the timetable could not be met. OLYMPIC might have become a protracted campaign and required additional troops. These reinforcements probably would have been drawn from the units designated for CORONET. CORONET also called for the employment of the lst Army, which was slated for transfer from Europe. Any problems in the redeployment schedule of troops from Europe or the United States also might have delayed CORONET. In spite of these problems, it would still be necessary to exert maximum pressure on the Japanese by reducing their will and capacity to resist and by not allowing them time to consolidate their defenses. In accordance with this reasoning, on 27 June 1945 the JWPC submitted to the JPS a plan, JWPC 363/1, which outlined the possible seizure of the vital industrial region of northwestern Kyushu by a force of 11 infantry divisions, one armored division, and a parachute regimental combat team as an alternative to CORONET.1 Northwestern Kyushu was a prime target for a number of reasons. It was the center of Japan's steel industry, and also contained important shipbuilding, chemical, and coal industries. From a strategic standpoint, the seizure of the area offered many advantages. It would open the Sea of Japan to the Allies, which would make possible a route to the 126 127 Soviet Maritime Provinces as well as further isolate Japan from the Asian mainland. Bases for up to 1,100 aircraft existed or could be built, thereby increasing the air effort against targets in Honshu, Shikoku, and Korea. An assault upon northwestern Kyushu might force the Japanese to commit troops from central Honshu as reinforcements, which would thereby reduce the resistance to any subsequent invasion of the Tokyo Plain. In conjunction with OLYMPIC, this operation would result in the complete occupation of Kyushu and the destruction of approximately one-third of the Japanese troops in the Home Islands. This would release American troops for employment elsewhere, such as in shore-to—shore assaults on western Honshu from newly-acquired bases in northwestern Kyushu. The main disadvantage of the plan was that it would interfere with preparations for CORONET and delay its execution. From a tactical standpoint, the assault area was within easy range of aircraft based in southern Kyushu, while terrain features would make it possible to isolate the beachhead to prevent enemy reinforcement. The greatest disadvantage was the shallow, island-studded waters near the invasion area. Approaches to the beaches could be easily mined or defended by shore batteries, and there was little maneuver room for ships to evade enemy air attacks.2 Northwestern Kyushu contains a number of small coastal plains, backed by low hills and mountains. These plains are generally isolated from each other, connected only through 128 narrow passes. One of the plains is in the vicinity of the large city of Fukuoka, and was suitable for the employment of mechanized forces. Heavy urbanization and extensive rice paddies, however, might have inhibited the full exloitation of mechanized forces. The coastline varied, having low beaches in some areas and steep cliffs in others. There were a number of good beaches near Fukuoka, but the approaches to these were covered by a number of small offshore islands. These islands would have to be occupied in order to gain unimpeded access to the beaches. The highest mountains in the area were the Seburi chain, southeast of Fukuoka, with peaks of up to 3,500 feet. Such mountains, along with thei lower foothills, offered good defensive positions for the Japanese, but once they were seized, the Americans could use them to defend the beachhead. There were no significant streams or rivers in the region. The projected invasion date of 1 March 1946 was a compromise in regards to the weather, with each element (ground, sea, and air) having the optimum operating conditions during different months. Fall and early winters were best for ground forces, for the rice paddies would be dry. Summer and fall offered the best flying weather, while May, June, and July offered the best sea conditions for naval operations. In terms of timing, however, the Americans could not have waited seven or eight months after OLYMPIC to invade northwestern Kyushu. It was necessary to exert unremitting pressure on the Japanese, so the earlier the invasion took 129 place, the better. The greatest obstacle for a March invasion date were adverse sea conditions, with waves running six feet or more. In order to support the forces ashore, the early seizure of a port was essential. The best ports in the region, going from east to west, were Wakamatsu, Fukuoka, and Karatsu. Wakamatsu had the greatest cargo-handling capacity (80,000 metric tons/20 hour day), was close to the strategic Shimonoseki Strait, and had two airfields located less than ten miles away. There were, however, far more disadvantages. The sea approaches to the port were narrow, the anchorage was" limited, and there were no good landing beaches in the area.. There were heavy shore defenses around Shimonoseki Strait, and terrain features and extensive urbanization would constrain maneuver by the invaders.3 Fukuoka, approximately forty miles southwest of Wakamatsu, had considerable advantages. The port could handle 32,400 metric tons of cargo a day, and Fukuoka Bay offered a good anchorage. There were five airfields near the city, and the coastal defenses were lighter than at Wakamatsu. There were many good landing beaches in the area, and the city was located in the center of a long coastal plain, which allowed for plenty of maneuver room and two avenues of approach to the city. As for the disadvantages, the numerous small offshore islands and the hills and mountains in back of the plain offered the Japanese good defensive positions.‘ 130 The westernmost port, Karatsu, could handle 7,200 metric tons of cargo a day, and had the lightest defenses of the three ports. Like Wakamatsu, however, Karatsu had considerable disadvantages as the primary objective. The sea approaches were restricted, and there were no suitable landing beaches. The nearby hills and mountains commanded the landing areas, restricted maneuver, and blocked “passage towards Shimonoseki Strait. Lastly, there were no airfields nearby. Based on these criteria, Fukuoka was selected as the main objective of the invasion.5 The next problem the JWPC faced was the selection of the main landing area. There were three choices: in the immediate vicinity of Fukuoka Bay, or west or north of the city. Landings at Fukuoka Bay presented many obstacles. The area was heavily defended and had poor approaches to the beaches. The terrain dictated a series of small, independent operations. Lastly, the Japanese could move reinforcements into the area from three directions. This option, therefore, was quickly rejected. ' The second choice, main landing on the peninsula west of Fukuoka, also was rejected. Although there were a number of good beachesfl the approaches to them were less than ideal. The road network in the area was inadequate for a large-scale mechanized assault. Lastly, the shortest route to Fukuoka passed through a corridor ranging in width from four to six miles, which contained numerous rice paddies and good defensive positions for the Japanese. While this area was 131 not suitable for the main landing, the JWPC judged it to be suitable for a secondary landing. The third choice, the main landing north of Fukuoka, was by far the best. There were long beaches, and good roads only a short distance inland. Once the surrounding hills have been seized, the American forces could strike out in two directions: southward towards Fukuoka and eastward towards Shimonoseki Strait. It would be necessary, however, to occupy a number of the offshore islands to destroy any enemy shore batteries that could interfere with the landings. This option was used as the basis of the invasion plan.6 During the preliminary phase of the invasion, approximately 4,200 carrier-based and 2,800 land-based aircraft from southern Kyushu would attack Japanese air and naval forces, lines of communication, and coast and beach defenses in the invasion area. Between 0-25 and 0-8, minesweeping operations would be carried tout around the approaches to the landing beaches. On D-3, six fast carrier task groups would enter the Sea of Japan via Tsushima Strait to conduct attacks against enemy rear bases to destroy any aircraft and shipping they encountered. These attacks would be repeated as necessary.7 The second phase of the operation, which would last from D-8 to D-l, called for employment of three infantry divisions to seize a number of the offshore islands that commanded the approaches to the landing beaches. Enemy garrisons and shore batteries would be destroyed in the process. Orono and 132 Oshima would be attacked on 0-8, Katsu and Aino on 0-4, Genkai on 0-2, and Hime on 0-1. Land-based artillery would be emplaced on Katsu and Aino to provide fire support for the main landings. On D-Day two corps consisting of two infantry divisions each would carry out the main landings north of Fukuoka. One corps would land between Ku Point and Fukuma, seize the airfield near Tsuyazaki, and then fan out to the north and east to secure the northern portion of the final beachhead line. The second corps would land between Fukuma and Shingu, seize the 0-1 line and, in conjunction with the secondary" landing west of Fukuoka on D-Day, seize Fukuoka and thei remainder of the final beachhead line. If the seizure of Fukuoka was delayed, it might have been necessary to advance further north to seize Jino Island and establish an advanced anchorage at Konominato Bay. The secondary landings consisted of four separate operations. On D-Day, a corps of two divisions would land near Cape Mitsuise and initially seize the 0-1 line. After seizing the 0-2 line, this force would advance eastward and, in conjunction with the main effort, seize Fukuoka and the remainder of the final beachhead line. A reinforced battalion would land east of Kushi Point to seize the coastal railway and road to prevent the movement of enemy troops from the southwest. Two airborne battalions would land near Yatanda and Magaributchi to seize key road junctions. On D+3, an infantry division, support by aircraft and land-based 133 artillery, would seize Shiga and Nokono Islands, thereby gaining control of the entrance to Fukuoka Bay.8 After the final beachhead line was secured, it would be held by minimal forces, while the bulk of the assault troops would complete the destruction of enemy forces in northern Kyushu, seize and hold the key industrial area of Mjoi-Kokura-Yawata-Wakamatsu, and, in conjunction with American troops in the south, complete the destruction of all enemy forces on the island. Eventually the northern and southern forces would meet, most likely on the eastern coastal plain. Once the occupation of Kyushu was completed,"~ preparations would be for further ground operations in the: Home Islands. Air forces would be built up to carry out bombing missions against targets in the other Japanese islands and on the Asian mainland. Naval forces would operate against Japanese naval and merchant shipping and open and maintain a route to Soviet Far Eastern ports. The JWPC realized that since northwestern Kyushu was vital to the Japanese they would make a determined effort to defend against a landing. The planners estimated that, following OLYMPIC, enemy ground strength on the island would consist of ten to twelve understrength divisions, plus home guard units. The bulk of the troops would probably be involved in a holding operation against American forces in the southern part of the island, but three or four divisions might be available in the northern part of the island to oppose the landings. Attacks against enemy LOCs would make 134 WRAILROAD MAIN ROAD (9 AIRFIELD RESERVE I AIRFIELD SITE PHASEII XX .CQ SHIMONOSEKI 0mma xxx SHIMONOSEKI 3DIVS — Ji. “""‘~.‘ O-shima $smma Ashiya Wakamatsu Tobata‘\/ / Orono- — ' AREA TO BE D—8@shima D 8 0—4 0,;0 ‘ , ‘7 KOKURA I o YAWAT OCCUPIED XX“ \ .. A IN PHASE IV a " ~ @ I o I 0 4D|VS PHASE HI omv 'm m I <7 Aino- ® E shimaD— 4 I Naokata D+3 Yukuhashi Q 0— 2 .‘~fi>X&x © Genkai© Shiga- zDIVS shima© ©:hima ' Kofukuro I, D DAY u" : \_ N k ...- \ Iizuka , Ida n -§fi%: FUKUOKA I I owe WAN \__’, D— —1 FUKUOK . _ Hachi a © © © Um! Q 1 I y Nakatsu D DAY H' , Okuma u. Ime— o I II shima 0—1 ‘ 3% ‘ \ ‘ I I .,,I [7 I Fulsukaichi Karats F ”0_2 4L (9 40 II 63% \§e AmaH I I AD L 3:] @ Tosu I Ochi Tanushimaru M MAP 9. PLAN FOR THE INVASION 0F NORTHWESTERN KYUSHUIJWPC 363/1) 135 reinforcement difficult, but units might be transferred piecemeal from the neighboring islands. Most of the Japanese air strength would have been expended in opposing OLYMPIC, but several hundred aircraft still would have been available to attack the landing forces. Only a few units of the Imperial Navy might have been available to oppose the invasion, but they would have been quickly eliminated. Extensive minefields posed the greatest naval threat to the invasion forces.9 A Since it was probable that OLYMPIC Would have required reinforcements from the troops designated for CORONET, the- latter operation would have been delayed. The northwesternt Kyushu operation probably would have been the next step in the conquest of Japan after OLYMPIC. A successful operation would have dealt a serious blow to the Japanese war effort, but there was little the Japanese could have done to prevent it. The operation would not only have given the Americans complete control of Kyushu but also wouldhave destroyed major enemy forces. CHAPTER 11 OPERATIONS FOLLOWING CORONET While American planners hoped that CORONET, or, better still, OLYMPIC, would bring about a Japanese surrender, they did not ignore the possibility that Japan might continue to resist after the successful completion of CORONET. In order to be prepared for such a contingency, in July 1945 the JWPC drafted a report, JWPC 333/1, which outlined possible actions the United States could take if the Japanese did not surrender after CORONET. The plan outlined measures to reduce Japanese will and capability to resist by intensifying the blockade and bombardment of Japan and the execution of large-scale amphibious assaults, which, together with exploitation from the lodgments in southern Kyushu and the Tokyo Plain, would result in the destruction of major enemy forces and the seizure of key areas} The JWPC listed five potential targets for seizure. They were, in order of priority, the Shimonoseki Strait region of Kyushu, the Osaka-Kobe-Kyoto area of central Honshu, the Nagoya area of Honshu, the .Hakodate-Aomori-Ominato area of Honshu and Hokkaido, and the Sapporo Plain of Hokkaido. The JWPC believed that the Japanese would probably expend almost all of their forces in resisting OLYMPIC and CORONET, and that no significant forces would remain elsewhere in Japan. They did not base their plan on this assumption, however, but on the assumption that the Japanese might still have substantial forces in existence 136 137 HOKKAHX) OSAPPORO Sih AREA ARMY V MURORA 1 Iniantty Division 1 Depo Div sion )1!- KODATE IIIII AREA ARMY 1 lniantry Division I epo Division HONSHU W 1 lnIanlry Division 4 Depot Divisions 5 I 12Ih AREA ARfl ’ Equivalenl cl 6 Divisions 13th AREA ARMY 4 lnianIry Divisions -9 2 Depoi Divisions 23:33:27“ ALLIED—OCCUPIED AREAS 8 Divisions "”0 W MAP 1o. ESTIMATED JAPANESE TROOP DISPOSITIONS. POST-“CORONET” (JWPC 333/1) 138 elsewhere in Japan after CORONET. Therefore, the JWPC estimated that the Osaka-Kobe-Kyoto, Nagoya, and Hakodate-Aomori-Ominato operations would each require eight divisions, the Shimonoseki Strait operation, nine divisions, and the Sapporo Plain, five divisions. If possible, these operations would employ troops already in the Western Pacific, in order to minimize the logistics burden and to, avoid the use of the strategic reserve based in the United States.2 The first attack was tentatively scheduled for 1 July 1946, approximately four months after the launching of CORONET. The JWPC listed a number of factors that would determine the selection of the first target for assault. First was enemy troop dispositions. The planners estimated that the largest concentrations of intact enemy forces would be in the Nagoya and Osaka-Kobe-Kyoto areas. These formations would have to be reduced considerably through air strikes before a successful attack could be mounted. Such a condition would probably not exist for some time, so it was unlikely that either area would be the first choice. Second, the effects of air and naval bombardments might so severely damage some of the potential target areas that they would be of little use to the Japanese, thereby making any landings unnecessary. Another factor was the possible need for a passage to the Sea of Japan, since by the conclusion of CORONET the Soviet Union would either be at war with Japan or on the 139 verge of it. If such a passage was deemed necessary, then the Shimonoseki Strait operation, which would result in the control of Tsushima Strait, or the Hakodate-Aomori-Ominato and Sapporo operations, which would result in the control of Tsugaru Strait, would be likely candidates for assault. A successful exploitation from the OLYMPIC lodgment, however, might make large-scale landings in northern Kyushu unnecessary.3 The final consideration the JWPC addressed was the importance of Hokkaido to the Japanese war effort. Because of its northern location, Hokkaido would have suffered little destruction from air and naval bombardment, and would be a , valuable source of food and other supplies needed by the Japanese army. The Hakodate-Aomori-Ominato and Sapporo operations would result in the interdiction of supplies from Hokkaido, though air strikes against lines of communications in northern Honshu and the Sea of Japan might have the same effect.4 JWPC 333/1 presented outline plans for the seizure of Shimonoseki Strait, Nagoya, the Hakodate-Aomori-Ominato area, and the Sapporo Plain. It included a discussion of the seizure of the Osaka—Kobe-Kyoto area, but it was not a detailed plan like the others. SHIMONOSEKI STRAIT The seizure of northern Kyushu would result in complete American occupation of the island, the destruction of significant enemy forces, and the severance of Japanese 140 communications with the mainland from Korea southward. It would also give the Americans access to the Sea of Japan, either to support the Soviets or to launch attacks against western Honshu. The invasion plan outlined in JWPC 333/1 was a modification of an earlier plan, JWPC 363/1. During phase I, some 1,500 carrier-based and 2,800 land-based aircraft operating from southern Kyushu would attack targets in and near the invasion area. Minesweeping of the sea approaches would commence on 0-16 and would continue until all of the surrounding waters were cleared. Six fast carrier task-" groups would enter the Sea of Japan on 0-3 to carry out strikes against enemy rear areas until D-Day.5 Phase II consisted of the seizure of four small offshore islands that controlled the approaches to the landing beaches. On D-8, one division would seize Orono and Oshima, and on D-4 another division would seize Katsu and Aino. Enemy troops and coast defenses would be destroyed, and artillery placed on Katsu and Aino to support the main landings. Phase III consisted of the landings themselves. On D-Day, a corps of two divisions would land between Ku Point and Fukuma and seize the airfield near Tsuyazaki and the northern portion of the final beachhead line. Another corps of two divisions would land further south, between Fukuma and Shingu, and advance to the 0-1 line. The two corps, in conjunction with a division that would land on order west of 141 WRAILROAD MAIN ROAD 6) AIRFIELD I AIRFIELD SITE B o A PHASE II _GO SHIMONOSEKI 0”“ xxx SHIMONOSEKI. D—8 { _ _ Jino- mnN‘ o zolvs 0‘5“”“3 $5M” “Shh“: wakamats" T°ba‘a~—/ / AREA TO BE _ o- _ D 8®sififi$a XXX D 4 Orio 0 KOKURA (I OCCUPIED o - YAWATA IN PHASE IV \ 5. .... E\ (9, PHASE ”I ””3”" V RESERVE ° 0 XX Tsu zaki xx D—4 ‘7 Aino- XX XXX Shlma® I Naokata M Y . XX 2 [)le D DAY XXX ukuhaShI G ka'- - _ E sifiKI‘na' Q gggifig ‘ Kofukuro I '0 ON 4%" ‘0 ORDER ‘s l \ __. Iizuka Nokono " ‘ Ida -Shima® FUKUOKA I \ l Goto WAN ~_’,v FUKUOK _ _ - ® (9 UmI Q 1 I Hachiya Nakalsu HQ Okuma «a Ime- ’ shima 0'— A I E0 ‘ \ l I, . O ’ “I Futsukaichi Karats I”O'—2 40“. ’864 © 69764 \’\‘\Q’ Amaki ® Tosu I Ochi Tanushimaru fflfiw M M MAP 11. PLAN FOR THE INVASION OF THE SHIMONOSEKI STRAIT, AREA(JWPC 333/1) 142 Fukuoka, would seize the city and the remainder of the final beachhead line. If there was any delay in opening Fukuoka Bay, troops would advance northward to seize Jino Island and secure Konominato Bay for use as an anchorage.6 Secondary landings would take place, on order, at four separate locations to support the main landings. A division would land west of Fukuoka in the vicinity of Cape Mitsuise and advance to the 0-2 line. In conjunction with the troops from the main landings, this division would participate in the seizure of Fukuoka and the final beachhead line. Also on order, one of the divisions that conducted the phaSe II operations would seize Genkai, Shiga, and Nokono islands to gain control of the entrance to Fukuoka Bay. During phase IV, the invasion forces would exploit their lodgment. They would seize and hold the key industrial area around Shimonoseki Strait, destroy any remaining enemy forces, and, in conjunction with American forces in southern Kyushu, complete the occupation of the island. Air bases would be established to conduct strikes against Japanese-held areas in the Home Islands and the Asian mainland, and preparations would be made for shore-to-shore attacks against other areas in Japan.7 The JWPC estimated that, at best, the Japanese would have the equivalent of eight divisions in Kyushu. Seven understrength divisions would be employed against American forces in the south, while three divisions in fair condition and a depleted depot division would be deployed in northern 143 Kyushu to oppose the invasion. These troops would be augmented by lightly-armed reservists and home-guard units. The Japanese navy and air force would offer only scattered resistance, having expended the bulk of their forces against OLYMPIC and CORONET. Regardless of the number or state of the defenders, a determined resistance was expected.8 NAGOYA Nagoya was the third-largest city in Japan, and an important manufacturing center, especially for aircraft. Ise Bay is the most prominent geographical feature of the region, and is surrounded by the second-largest lowland area on Honshu. The Ise Lowlands consist of three plains: the Nagoya Plain at the head of the bay, the Okazaki Plain to the east, and the Matsuzaku Plain to the west. Surrounding mountains to the east, north, and west made access to other areas of Honshu difficult, which ruled out an overland advance from the Kanto Plain lodgment against Nagoya. An amphibious assault was deemed the best way to seize and occupy the area.9 Under the ”worst-case scenario" envisioned by the JWPC, the Japanese might have four infantry and two depot divisions, Iplus fortress troops and home-guard units, deployed in the Nagoya area. In order to obtain the desired 3:1 superiority over the defenders, an invasion force would have to consist of fifteen to eighteen divisions. In the opinion of the JWPC, the prospect of launching such a large attack so soon after the Kanto Plain operation was VVL Saki Nagahama Glfu OI Inuyama Ogak T] i lm lch mlya a lkone . Dachl O O Seto O YOkaIchl NAGOYA A G) 0 © © Koroma Minakuchi Kuwana lwatsu Yokkaich Yawata 0 f o : Okazaki (Q a \ © \ k Tokoname Oham 0 © ’ \Han a MIya I IS E I I ’ I © ’1 WA N ' Toyohashi Ueno ’ ‘ ATSUMI WAN (9 III R» - Utsumi C Tsu ~-" 0 ® 1. 1 III \ 0 II Hlsa Q \‘ XX (9 ‘s s D + 5 ‘ RESERVE “. * ' ‘ 5: X17; / Matsu‘zaka I\\ <2 0 XX © \ as??? x E . \ Floatin XX 9 o XX _ AY Uilyam da Toba 0‘2 D D @ 6 _ XX DAY Prepared to mount \ II from Kanto Plain \~‘ _ 0 O AIRFIELD I J. ‘ +H-H—RAILROAD -—-- MAIN ROAD MAP 12. PLAN FOR THE INVASION OF THE NAGOYA AREA (JWPC 333/1) 145 "unacceptable." American airpower would have to be employed on a large scale to reduce the strength and effectiveness of the Nagoya garrison before any invasion was attempted. These air strikes would constitute phase I of the plan.‘0 Phase II consisted of landings on D-Day by three divisions to seize control of the entrance to Ise Bay. One division would occupy the western tip of the Atsumi Peninsula. A corps of two divisions would seize Suga, Toshi, and Kami islands, and then execute a series of shore-to-shore landings to seize Tobe and Futami and establish a lodgment. In phase III, beginning at 0+5, a division would land at the southern tip of the Chita Peninsula and advance northward to the Tokaido railway line, either by overland advance or in combination with shore-to-shore amphibious movements. At the same time, the Atsumi force would move eastward along the peninsula to the Umeda River, while the Toba force would advance up the western shore of Ise Bay to the Kise River, either through an overland advance or in combination with shore-to-shore movements. Phase IV, which would begin around D+20, called for the employment of the entire assault force, including the reserves. During this phase, the city of Nagoya and the Nagoya Plain would be occupied, as well as the Okazaki Plain, the territory northeast of Atsumi Bay, and the main highway between Ozaki and Lake Biwa. Control of the mountain passes would be vital to any later overland advance against the Osaka-Kobe-Kyoto region. 146— Foyama Okazaki “ . 'I' ToythIShK-fi m C: Hamm‘m‘5U ' Okayama o Q W I) <7 {$3 AWAJI— ° SHIMA °Takamatsu Tokushima “"H‘HRAILROAD —T—MA|N ROAD © AIRFIELD MAIN LAND ROUTES —TO OSAKA LOWLANDS RESTRICTED CORRIDORS, mFORTlFll—ZD ZONES MAP 13. ORIENTATION MAP, OSAKA—KOBE-KYOTO AREA 147 OSAKA-KOBE-KYOTO The lowlands of central Honshu, or Kansai Plain, contain the important cities of Osaka, Kobe, and Kyoto. The seizure of this area would contribute greatly to American domination of Japan through the destruction of major enemy forces. However, geography presented a number of serious obstacles to a successful attack. The area was ‘bounded by rugged highlands on the east and north, and on the south by the narrow waters of the Inland Sea. The JWPC considered three possible routes into the Kansai Plain: from Wakayama on the Pacific to the Osaka Plain, from Wakasa Bay on the Sea of Japan to the Biwa and Kyoto basins, and from the Nagoya area to the Biwa and Kyoto basins. There were good beaches near Wakayama and Osaka, and the port of Wakayama would be adequate for supply until Osaka was seized. Among the disadvantages of the area were strong coast defenses along the Kii Channel and the entrance to Osaka Bay, Kitan Strait. The terrain inland from the beaches was rugged and would slow an overland advance. There were a number of good beaches along Wakasa Bay, with the areas near Maizaru and Amino close to the best routes betweEn the Sea of Japan and the Kyoto Plain. The ports of Amino, Miyazu, and Maizaru seemed adequate from a logistics standpoint, but the roads that led inland from the ports were narrow, which would make it difficult to support a large invasion force. Additionally, the mountainous terrain immediately behind the coast would force the invaders into 148 narrow "choke points" that the Japanese could defend with minimal forces."1 The third option assumed the establishment of a lodgment in the vicinity of Nagoya before undertaking operations against the Kansai Plain. The seizure of a mountain pass near Sekigahara would permit access to the Biwa basin. Other passes further south could be seized to make supporting drives possible, though the terrain was not as favorable. The JWPC rejected the assaults from the Pacific and Wakasa Bay, for, in its opinion, the results of such an action would not justify the levels of effort required. An " overland advance from the Nagoya area was considered the best. course of action. The JWPC estimated that enemy strength in the Kansai Plain would amount to no more than one infantry and three depot divisions, plus assorted other units. In the opinion of the JWPC, the forces that seized Nagoya would need only minimal augmentation to be able to seize Osaka, Kobe, and Kyoto.‘2 HAKODATE-AOMORI-OMINATO Seizure of the Tsugaru Strait area of northern Honshu and southern Hokkaido would give the Americans a route to the Sea of Japan and the Soviet Far East and sever the flow of supplies from Hokkaido to enemy forces elsewhere in Japan. Of the four plans outlined in JWPC 333/1, this was the most complex, involving landings at fourteen sites. The initial objectives of the assault were to secure a lodgment containing suitable airfields and the port of +H++RA|LROAD ———MAIN ROAD O AIRFIELD I AIRFIELD SITE Shlrluchl Fukuyama TAPPI— ED SAKI Kodomarl I i Nohe“ RESERVE .l' Ajlgasawa XX XI“ I O Shichlnohe Misawa Sambongl I FUkaura HIrosakI MOmOIShI © ' Gonohe Hachinohe * LAKE TOWADA Sannohe HachImorI I, . -Ono «’"m Q, MAP 14- PLAN FOR THE INVASION OF THE HAKODATE—AOMORl—OMINATO AREAUWPC 333/1) 67L again p bl h III I 150 Ominafo and Hakodate and the anchorage of Mutsu Bay. During phase I of the assault, preliminary air and naval bombardments would be conducted in the vicinity of the landing areas. Diversionary strikes would also be conducted against the towns of Muroran and Tomakomai in east-central Hokkaido.‘3 Phase II consisted of the main landings. On D-Day, four divisions would land at sites 1, 2, 3, and 4. The first three landings would secure a beachhead on the Shimokita Peninsula and capture Ominato. The diviSion landing at site 4 would put ashore forces sufficient to destroy enemy. coast defenses near Oma-saki, and then prepare to conduct further operations. Another division would land at sites 5 and 6 to destroy enemy coast defenses. Phase III consisted of the seizure of Hakodate, the destruction of remaining enemy coast defenses, and minesweeping of Tsugaru Strait. A corps of two divisions would land at site 7 around D+S to seize Hakodate and establish a defensive position. Later, these troops would expand their lodgment to the north and southwest. As soon as possible after D-Day, and in no case later than D+5, the division that landed at site 4 would land troops at sites 8 and 9 to destroy the coast defense along Tairadate Strait. This division would also carry out further landings at sites 10, 11, and 12 to destroy enemy coast defenses and troops. A reinforced battalion would be left at each site for a garrison. On order, the division that landed at sites 5 and "- 151 6 would conduct landings at sites 13 and 14 to destroy the remaining enemy coast defenses along the strait. Once the assault phase was completed, operations would be carried out to destroy any remaining enemy forces and to consolidate the lodgmentj‘ The JWPC estimated that the Japanese would probably have one division and one depot division in Hokkaido, as well as a division in northern Honshu and a depot division further south near Sendai. These units would be augmented by coast-defense and fortress troops as well as lightly-armed reservists and home guard units. Interdiction of lines of communication would severely limit Japanese ability to reinforce the invasion area. In the opinion of the JWPC, neither the Japanese navy or air force would be capable of offered effective organized resistance.‘5 SAPPORO PLAIN The Sapporo Plain is the largest on Hokkaido, stretching across the island and offering easy passage between the Pacific and the Sea of Japan. There were five airfields and seventeen airfield sites in the area. The ports of Muroran on the Pacific and Otaru on the Sea of Japan were adequate to supply an invasion force. A lodgment in the Sapporo Plain would give the Americans not only control of the most important section of Hokkaido, but also control of Hakodate and Tsugaru and La Perouse straits. If control of Tsugaru Strait was deemed necessary, the Sapporo operation would make more sense than the Hakodate-Aomori-Ominato operation, since +o+o+RAILROAD -————MAIN ROAD O AIRFIELD l AIRFIELD SITE Manta exPLOITATION ,j — - —’————--_ /’— ‘--n / / - / . Ishlkatl Yolchl/ I...” lSHIKARI WAN / 4'" luv" Otaru I [w\ x“ \ \ . \ § \“ ~~~~ K \‘ SAPPORO ”r V. ' ‘ BEACHHEAD‘ LINE « Kutchlan X \ HIgashI-Kulchlan \ .. I \\ \\ \\ J \ \ \ “’Wanishl XX Muroran a 01 § \/ DDAY [g Vfiixx I ._ MAP 15. PLAN FOR THE INVASION OF THE SAPPORO PLAIN (JWPC 333/1) ZSL 153 it required fewer troops and a simpler amphibious assault. During phase I (0-10 to 0-1) air and naval forces would isolate the invasion area and reduce coast defenses near the landings zones. The port of Hakodate would be neutralized to prevent the Japanese from transferring reinforcements from Honshu. During phase II, one division would land east of Wanishi and seize Muroran. A second division would land west of Tomakomai, seize the town and airfield, and advance inland to seize the airfield at Chitose. In phase III, the invasion forces would exploit their lodgment. Any remaining enemy forces in the plain would be eliminate, naval bases would be established at Otaru and Hakodate, and either Tsugaru or La Perouse Strait would be opened.‘6 The JWPC estimated that the Japanese would have one division and one depot division stationed in Hokkaido. Of these forces, an infantry regiment and the depot division might be in position to contest the landings. Such forces could do little against the superior number of the assault force. Isolation of the assault area would severely limit the ability of the Japanese to move in reinforcements}7 CHAPTER 12 SUMMARY AND CONCLUSIONS The JCS considered an invasion of the Japanese homeland necessary in order to bring about an unconditional surrender by the Japanese government. Prior to an invasion, a tight naval blockade would be established and a heavy aerial bombardment campaign would be carried out against military and industrial targets to reduce Japan's ability to resist. SOme prominent officers, among them King, Arnold, and Leahy, were not completely convinced of the need for an invasion and maintained that Japan could be defeated through a blockade and bombardment strategy. Such an approach, however, might have required considerable time to have a decisive effect. The first mention of an invasion occurred in May 1943. The topic was examined a number of times during the next year, but in an abstract way, since the Allies were far from the Japanese homeland. In June 1944, however, invasion became a definite goal of American strategy. This policy was set forth in JCS 924, which examined the establishment of possible lodgments in Korea, China, Hokkaido, and Kyushu from which to support landings near Tokyo. After examining the advantages and disadvantages of each area, the JPS recommended landings in Kyushu on 1 October 1945, to be followed by landings near Tokyo on 31 December 1945. Positions in the Bonins and Ryukyus would be seized during the spring of 1945 to support the Kyushu landings. During the summer of 1944 the JWPC drafted a plan for an 154 155 attack on Kyushu. This plan, JWPC 235/3, envisioned an assault by eight divisions to establish a lodgment in the southern portion of the island. This plan served as the basis for Operation OLYMPIC, which called for landings by thirteen divisions in southern Kyushu and nearby islands around 1 November 1945. Planning and preparations for OLYMPIC were well-advanced when the war ended. The issue of who would be in overall command of the invasion received a great deal of attention from the JCS and their various planning bodies during early 1945. The Navy wanted to form a separate Japan Area Command, whose commander-in-chief would be responsible for the invasion. The Army, on the other hand, wanted to consolidate all Army forces in the Pacific under General MacArthur and all naval forces under Admiral Nimitz. In April 1945, a command organization similar to that advocated by the Army was adopted. During the summer of 1945, the Marianas-based B-29's were formed into a third major command, the U.S. Army Strategic Air Forces, under General Spaatz. This command structure would have overseen the invasion of Japan. On 25 May 1945, the JCS issued a directive to Admiral Nimitz and Generals MabArthur and Arnold to begin planning and preparations for OLYMPIC. MacArthur would be in command of the land operations, while Nimitz would oversee the naval and amphibious phases of the campaign. During the spring and summer of 1945 the JWPC worked on plans for operations against other areas of the Japanese home 156 islands. In May 1945 a plan for the invasion of the Tokyo Plain with twenty-three divisions, JWPC 263/4, was submitted to the JPS. A plan for the invasion of northwestern Kyushu utilizing eleven divisions, JWPC 363/1, was also submitted as an alternative to the Tokyo Plain. While it was hoped that the invasion of the Tokyo Plain would bring about an unconditional surrender, the JWPC acknowledged the possibility that the Japanese might continue to resist after the loss of Tokyo. In response to this contingency, the JWPC drafted a plan, JWPC 333/1, which offered plans for the seizure of certain key areas in order to destroy major. enemy-T forces and deny the enemy important industrial and strategic areas. Among the possible targets were northwestern Kyushu, Nagoya, Osaka-Kobe-Kyoto, the Ominato-Aomori-Hakodate area of Honshu and Hokkaido, and the Sapporo Plain of Hokkaido. Both the United States and Japan were prepared for a bloody campaign for the homeland. The Japanese had thousands of aircraft for use in suicide attacks against the invasion forces, and nearly two million regular troops. These troops were supplemented by reservists and home-guard units armed with a variety of weapons, including spears, swords, and ancient single-shot muskets. The Japanese militarists were determined to continue the war and resist any invasion, primarily out of pride and national honor. Some politicians, on the other hand, realized the war was lost and tried a variety of ways to reach a settlement. The dropping of the atomic bombs on 157 Hiroshima and Nagasaki, together with Emperor Hirohito's decision to accept the Allies' Potsdam Declaration, brought the war to an end and made an invasion unnecessary. The JCS considered Soviet intervention in the war against Japan as vital to the success of an invasion. The Red Army would contain and destroy Japan's much-vaunted Kwantung Army in Manchuria, thereby making it unavailable for the defense of the homeland. It would also result in the destruction of forces that might not obey a surrender order from Tokyo and continue to resist. Lastly, occupation of Manchuria and Korea would deny the Japanese government a plance of refuge from which it could continue the war if the homeland became untenable. NOTES NOTES CHAPTER 1. EARLY THOUGHTS ABOUT AN INVASION 1. 10. 11. 12. 13. 14. JWPC 15, "Strategic Plan for the Defeat of Japan," 12 May 1943. Paul Kesaris, ed., Records ggthe Joint Chiefs of Staff. Part I: 1942-1945. The Pacific Theater. (Frederick, MD: University PublicatIOns of America, 1981). Hereafter referred to as JCS Records. Grace Person Hayes, The History of the Joint Chiefs of Staff in World War II: The War Against Japan. (Annapolis, MD: Naval Institute’Press, I982). P. 458. Hereafter referred to as Hayes. CPS 83, "Appreciation and Plan for the Defeat of Japan," 8 August 1943. JCS Records. JWPC 46/5, "Appreciation and Plan for the Defeat of Japan," 9 July 1943. JCS Records. Ibid. Ibid . CCS 313, "Appreciation and Plan for the Defeat of Japan," 18 August 1943. JCS Records. Hayes, P. 462 Ibid. CCS 313 CPS 86/2, ”The Defeat of Japan Within Twelve Months After the Defeat of Germany," 25 October 1943. JCS Records. Hayes, P. 499 Ibid. JCS 564, "The Defeat of Japan Within Twelve Months After the Defeat of Germany," 4 November 1943. JCS Records. 158 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 159 Hayes, P. 503 Fleet Admiral Ernest J. King, U.S. Navy and Walter Muir Whitehall, Fleet Admiral King: A Naval Record. (New York: W.W. Norton & Company, Inc., 1952). P. 598: and Fleet Admiral William D. Leahy, U.S. Navy, I Was There. (New York: Whittelsey House, McGraw-Hill Book Company, Inc., 1950). P. 259. Hayes, P. 504. Ibid. CCS 417,"Overa11 Plan for the Defeat of Japan," 2 December 1943. JCS Records. Ibid. Barbara W. Tuchman, Stilwell and the American Experience in China, 1911-45. (New York: The Macmillan Company, 1971.) P. 408-409. Samuel Eliot Morison, The Two-Ocean War: A Short History of the United States Navy in the Second World War. Boston: Little, Brown and Company, 1963.) P. 305. CCS 417, "Overall Plan for the Defeat of Japan," 2 December 1943. JCS Records. Hayes, P. 482-486. Hayes, P. 505-506. CHAPTER 2. SELECTING A TARGET 1. Samuel Eliot Morison, History of United States Naval Operations in World War II. Volume VIII: New Guinea and the Marianas, March 1944-August 1944. (Boston: Little, Brown and Company, 1975), p. 9. JCS 924, "Operations Against Japan Subsequent to Formosa,” 30 June 1944. JCS Records. Ibid. Ibid. Ibid. Ibid. Ibid. 160 Houghton Mifflin Vol. 6: A 81W Little, Brown 8. Ibid. 9. Ibid. 10. Ibid. 11. Ibid. 12. Ibid. 13. Ibid. 14. Hayes, p. 628. 15. Ibid., p. 629 CHAPTER 3. KYUSHU 1. JWPC 235/3, "Plan for Operation Against Kyushu," 4 September 1944. JCS Records. 2. Ibid. 3. Ibid. 4. Ibid. 5. Ibid. 6. Ibid. 7. Ibid. 8. Ibid. 9. Ibid. 10. Ibid. 11. Ibid; 12. Ibid. ‘ CHAPTER 4. STRATEGIC ISSUES 1. Winston S. Churchill, The Second World War, Triumph and Tragedy. (Boston: Company, 1953.) P.146-147. 2. Thomas B. Buell, Master of Sea Power: Fleet Admiral Ernest J. King. (Boston: and Co., 1980). P. 444. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 161 Ibid., P. 446. Hayes, P. 654. CCS 691, "British Participation in V.L.R. Bombing of Japan," 18 September 1944. Hayes, P. 654. JWPC 526/3, "British Participation in V.L.R. Bombing of Japan," 6 October 1944. Ibid. Hayes, P. 655. Hayes, P. 643 Buell, P. 446-448. JWPC 404/14, "Operations for the Defeat of Japan," 7 October 1944. Hayes, P. 655. Hayes, P. 656. JWPC 404/15, "Operations for the Defeat of Japan," 18 October 1944. Hayes, P. 656. ~ Hayes, P. 656. Ibid 0 JCS 924/5, "Operations for the Defeat of Japan," 27 October 1944. Hayes, P. 656. JCS 924/6, "Operations for the Defeat of Japan," 6 November 1944. Hayes, P. 657. JCS 924/7, "Operations for the Defeat of Japan," 6 November 1944. Hayes, P. 657. JCS 924/8, "Operations for the Defeat of Japan," 23 November 1944. Hayes, P. 657. CCS 417/10, "Operations for the Defeat of Japan," 1 Decembek 1944. Hayes, P. 657. JIC 224/1, "Japanese Capabilities and Reactions to an Assault on Hokkaido as Compared with an Assault on Kyushu," 18 October 1944. JCS Records. JWPC 398/1, "Plan for the Invasion of Northern Honshu (Alternative to Invasion of Southern Kyushu)," 9 August 1945. JCS Records. .1..— h—. 162 CHAPTER 5. COMMAND REORGANIZATION l. 2. 3. 11. 12. 13. 14. 15. 16. 17. Hayes, P. 687. Ibid. William Manchester, American Caesar:. Douglas MacArthur, 1880-1964. (Boston: Little, Brown and Company, 1978.) P. 435. Hayes, P. 688. Ibid. Hayes, P. 689. Ibid. Hayes, P. 690-691. Hayes, P. 691. JCS 1259/3, "Directive for Reorganization and Future Operations in the Pacific," 16 March 1945. Hayes, P. 692. Hayes, P. 692. Hayes, P. 692-693. Hayes, P. 693-694. Hayes, P. 694. Ibid. Ibid. Hayes, P. 695. CHAPTER 6. THE DECISION TO INVADE 1. Tuchman, P. 515. Hayes, P. 702. JCS 924/15, "Pacific Strategy," 25 April 1945. Hayes, P. 702. Ibid. Hayes, P. 702-703. 10. 11. 12. 13. 14. 15. 16. l7. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 163 Hayes, P. 703. Ibid. Ibid. Hayes, P. 703-704. Hayes, P. 704. JCS 1331/2, "Directive for Operation 1945. JCS Records. Ibid. Ibid. Hayes, P. 705. JCS 1331/2, op. cit. Hayes, P. 705 JCS 1331/3, "Directive for Operation 1945. JCS Records. 'OLYMPIC'," 14 May 'OLYMPIC'," 25 May JCS 1388/1, "Proposed Changes to Details of the Campaign Against Japan," 20 June 1945. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. JCS Records. 30. 31. 32. 33. 164 CCS 890, "Control and Command in the War Against Japan," 9 July 1945. JCS Records. JCS 1407/3, "Control and Command in the War Against Japan,” 16 July 1945. JCS Records. CCS 890/2, "Control and Command in the War Against Japan," 18 July 19 45. JCS Records. John Toland, The Rising Sun: The Decline and Fall of the Japanese Empire, 1936-1945. (New York: Random House, 1970). Vol. 2, P. 1032. CHAPTER 7. "OLYMPIC" 1. 10. ‘ 110 12. 13. 14. 15. 16. 17. 18.‘ K. Jack Bauer and Alvin D. Coox, "OLYMPIC vs. KETSU-GO," Marine Corps Gazette, V. 49, No. 8 (August 1965). P. 37. Ibid. Ibid. Ibid., P. 39. Ibid. Ibid., P. 41-43. Ibid., P. 44. JCS 1410, "Plan PASTEL," 6 July 1945. JCS Records. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. JIC 311, ”Defensive Preparations in Japan," 2 August 1945. JCS Records. ‘ Ibid . Ibid . 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 165 Ibid. Ibid. JIC 307, "Capabilities of Japanese Air Forces," 25 July 1945. JCS Records. Major General S. Woodburn Kirby, et. al., The War Against Japan. Volume V: The Surrender of Japan. (London: Her Majesty's Stationery Office, 1969.) Map Opposite P. 160. Ibid. Ibid. Ibid., Map Opposite P. 147. Denis Warner and Peggy Warner, with Commander Sadao Seno, Japanese Maritime Self-Defense Force (Retired), The Sacred Warriors: Japan's Suicide Legions. (New York: Avon Books, 1982.) P. 301 Ibid., P. 300. James Martin Davis, Top Secret: The Story of the Invasion of Japan. (Omaha, NE: Ranger Publications, 19860) P- 21.23- Clark G. Reynolds, The Fast Carriers: The Forging of an Air Navy. (New York: McGraw-Hill Book Company, 1968.) P. 383. CHAPTER 8. NORTHERN HONSHU JWPC 398/1, "Plan for the Invasion of Northern Honshu," 9 August 1945. JCS Records. Ibid. Ibid. Ibid. ‘ Ibid. Ibid. Ibid. Ibid. Ibid. 166 10. Ibid. 11. Ibid. 12. Ibid. CHAPTER 9. "CORONET" 1. JWPC 263/4, "An Outline Plan for the Invasion of the Kanto (Tokyo) Plain,” 5 May 1945. JCS Records. 2. Ibid. .3. Ibid. 4. Ibid. 5. Ibid. 6. Ibid. 7. Ibid. 8. Ibid. 9. Ibid. 10. Ibid. 11. Ibid. 12. Ibid. 13. Ibid. 14. Ibid. 15. Ibid; 16. Ibid. 17. Ibid. 18. JWPC 190/16, "Staff Study of Cover and Deception Objective for 'Coronet'," 26 July 1945. JCS Records. 19. Ibid. 20. JWPC 359/1, "Operations Preceding 'Coronet'," 8 June 1945. JCS Records. 21. Ibid. 22. 23. 24. 167 Davis, P. 18. JCS 1388/4, "Details of the Campaign Against Japan," 11 July 1945. JCS Records. Reynolds, P. 371. CHAPTER 10. NORTHWESTERN KYUSHU JWPC 363/1, "Invasion of Northwestern Kyushu," 27 June 1945. JCS Records. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. CHAPTER 11. OPERATIONS FOLLOWING CORONET JWPC 333/1, "Operations in Japan Following 'CORONET',‘ 26 July 1945. JCS Records. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. 12. 13. 1'4. 15. 16. 17. Ibid. Ibid. Ibid. Ibid. Ibid. Ibid. 168 B I BLIOGRAPHY BIBLIOGRAPHY Bauer, K. Jack and Coox, Alvin D. "OLYMPIC vs. KETSU-GO," Marine Corps Gazette. V. 49, No. 8. August 1965. PP. 32-44. Buell, Thomas B. Master of Sea Power: A‘Biographyof Fleet Admiral Ernest J. King. Boston: Little, Brown and Company, 1980. Davis, James Martin. Top Secret: The Story of the Invasion of Japan. Omaha, NE: Ranger Publications, 1986. Frank, Benis M. and Shaw, Henry I. History of U.S. Marine Corps Operations in World War II. vol. V: Victory and Occupation. Washington: Historical Branch, G-3 Division, Headquarters, U.S. Marine Corps, 1968 Hayes, Grace Person. The History of the Joint Chief of Staff in World War II: The Jar Against Japan. Annapolis, MD: Naval Institute Press, 1982. Kesaris, Paul, ed. Records of the Joint Chiefs of Staff. Pt. 1: 1942-1945, The Pacific Theater. Microfilm, 14 Reels. Frederick, MD. University Publications of America, 1981. King, Ernest J. and Whitehall, Walter Muir. Fleet Admiral King: A Naval Record. New York: Norton, 1952 Kirby, S. Woodburn, et. al. The War Against Japan. vol. V: The Surrender of Japan. London: Her Majesty‘s Stationery Office, 1969. Leahy, William D. I Was There. New York: MacGraw-Hill, 1950. Manchester, William. American Caesar: Douglas MacArthur, 1880-1964. :Boston: Little, Brown, 1978. Morison, Samuel Eliot. History of United States Naval Operations in World War II. vol. VIII: New Guinea and the Marianas, March 1944-August 1944. Boston: Little, Brown, 1953. Morison, Samuel Eliot. The Two-Ocean War: A Short History of the United States Navy in the Second World War. Boston: Little, Brown, 1963. 169 170 Reynolds, Clark G. The Fast Carriers: The Forging of an Air Nagy. New York: MacGraw-Hill, 1968. Toland, John. The Rising Sun: The Decline and Fall of the Japanese Empire, 1936-1945. 2 Vols. New York: Random House, 1970. Tuchman, Barbara W. Stilwell and the American Experience in China, 1911—1945. New York: Macmillan, 1970. Warner, Denis; Warner, Peggy: and Seno, Sadao. The Sacred Warriors: Japan's Suicide Legions. New York: Avon Books, 1982. HICHIGQN [M 13112 STATE UNIV. LIBRARIES WWMWMWWWWW 93017648043