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While the defensive perimeter of Japan was fighting Sho-Go operations as part of a delaying tactic, the Imperial General Headquarters was preparing a suicidal defense of the Japanese homeland. The defense plan Ketsu-Go called for destruction of the invasion fleet before enemy landings on the beaches with a combined air and sea attack. Furthermore, the plan divided Japan into seven additional defensive zones. To maximize the effectiveness of the limited resources available, the high command concentrated most of their assets on defending Kyushu and the Yokohama-Tokyo region on Honshu.24 The basic concept of the overall defense plan was to make the invasion of Japan as bloody as possible. After the victories at Iwo Jima and Okinawa, the American public started to question the extremely high casualty cost of taking those islands. The Japanese government saw this as an opportunity to force a more favorable peace settlement. By refusing to accept the unconditional surrender, Japanese officials believed
that forcing an invasion and creating more “casualties and destroying the morale of green units, America would be more flexible in her terms for ending the war.”25 The Imperial General Staff used the lessons learned from previous island campaigns and the Normandy invasion to analyze where the Americans would land and how to defend against it.
From previous landings, the Japanese learned that the Americans targeted areas where large number of forces could land at once, usually close to their overall objective. The capture of an airfield had priority early in the assaults, in order to place it back into operation quickly and provide close air support for ground troops. The invasion site had to offer room to maneuver, so the Americans could exploit their overwhelming advantage in heavy equipment. Unlike the Japanese, the Americans would not use surprise as a tactic; moreover, they would not avoid wellprepared defenses. After reviewing the advantages and disadvantages of all the possible landing sites, the General Staff concluded that the Americans would land on Kyushu in vicinity of Miyazaki, Ariake Bay, and the Satsuma Peninsula. Those three sites offered nearby airfields, the Miyakonojo plain for maneuver, and a protective harbor within Kagoshima Bay. 26 On June 6, 1945, Japan’s Supreme Council for the Direction of the War met to discuss the Army’s plan for the Decisive Battle. Lieutenant General Torashiro Kawabe, the Army’s Vice Chief of Staff, told the group that the tactics used to defend Saipan, Iwo Jima, and Okinawa had proved disastrous and that the Decisive Battle plan for Japan was “altogether different.” The Japanese labeled their defensive strategy as a Decisive Battle, which in reality was a plan for attritional warfare. While Japan had sustained tremendous losses, the Imperial Army remained a powerful fighting force with many and of its aircraft and airfields still operational. Kawabe emphasized that kamikazes would attack and destroy a quarter of the invasion force at sea, then Walker, Dilemma, p. 211.
Frank, Downfall, pp. 167-168.
focus their attacks on the troopships coming ashore. Those invaders who survived would die on the beaches. The Emperor received that “fight-to-the-end plan” on June 8 and gave his tacit approval.27 The Imperial General Headquarters then issued a directive on June 20 ordering field commanders to engage the enemy in close combat at the shoreline to neutralize his superior firepower.28 The Japanese defensive build-up was massive. Some fourteen divisions and eleven brigades moved into the Kyushu region. The Imperial Headquarters established three armies to defend Kyushu: the 56th in the north, the 57th on the southeast coast, and 40th on the southwest coast. The 16th Area Army had overall responsibility for the defense of Kyushu and concentrated its forces on the projected invasion sites at Miyazaki, Ariake Bay, and Satsuma Peninsula. In his final instructions for the so-called “Ketsu Operation,” Lieutenant General Isamu Yokoyama, Sixteenth Area Army Commander, ordered all coastal units to “fight to the death where they stood.” Each division would maintain a regiment size reserve. He ordered the use of tanks in support of a counterattack and as mobile artillery only. He emphasized that the Americans would deploy tremendous firepower, including tank, napalm, and naval bombardments to break Japanese defense.29 The primary weapons the Japanese planned to deploy against the American invasion fleet were the special attack units, which had first appeared during the battle of Leyte when the Japanese tried to stop the American landings with kamikaze attacks. To the Japanese, “a successful mission ended when they blew themselves up against an American ship.” The original suicide units consisted of navy and army aircraft with a bomb attached to each. The pilots flew their planes into enemy warships causing significant damage to the ships and crew.
Allen, Codename Downfall, p. 170.
Frank, Downfall, p. 166.
Ibid., pp. 169-174.
In January 1945, Japan’s Supreme Council for the Direction of the War decided to make suicide attacks a basic weapon and ordered Japan’s industry to “concentrate on converting all armament production to special attack weapons of a few major types.”30 While the Kamikaze plane remained the primary threat in the Japanese arsenal, the Japanese built various suicide weapons for use during the Decisive Battle, such as midget submarines that carried torpedoes or had packed bows with explosives and detonated on impact much like the Kaiten human torpedoes, which men piloted into enemy ships. The Imperial Navy also organized Water’s Edge Surprise Attack Forces that consisted of suicide explosive-laden swimmers who would destroy enemy landing crafts. Marine Advanced Units consisted of high-speed boats armed with two depth charges to attack enemy troop transports off shore.31 In the Decisive Battle for Japan, the Imperial Headquarters planned to deploy the “entire air strength into the battle on Kyushu.” This tactic would deny air support for the defense of Tokyo. Nevertheless, the Japanese planned to “saturate” the invasion area with hundreds of kamikazes. During the battle of the Philippines, suicide planes had used the mountainous terrain to enhance the elements of surprise, something they had lacked in long flights over water at Okinawa. The terrain on Kyushu would provide Japanese pilots excellent concealment en route to the packed enemy troopships close to shore. Based on the experiences at Okinawa and because of a lack of veteran pilots, the Japanese estimated that only one out of six planes of the 4000 available aircraft would hit an enemy ship, but the potential for causing mass casualties remained high.32 As on Okinawa, the Japanese Government planned to mobilize the entire civilian population into combat units, Special Guard Forces, Independent Companies, and Civilian Ienaga, Pacific War, p. 183.
Frank, Downfall, pp. 183-184.
Ibid., pp. 184-184.
Volunteer Corps. The military issued training manuals called “People’s Handbook of Resistance Combat,” which provided instruction on how to employ Molotov cocktails against tanks, how to use a rifle, and how to improvise weapons in the absence of small arms. Military trainers told mobilized schoolchildren, “Even killing just one American soldier will do. You must prepare to use the awls for self-defense. You must aim at the enemy’s abdomen.” Additionally, teachers told children, “If you don’t kill at least one enemy soldier, you do not deserve to die.”33 With the countrywide mobilization, the Japanese leadership guaranteed that many civilians would die in the ensuing invasion since American troops would have “to treat all Japanese as combatants or fail to do so at their peril.”34 Throughout the Pacific War, the Japanese fought with such ferocity and determination that the thought of invading the Japanese homeland was frightful. The campaigns the Americans waged across the Pacific only hardened Japanese readiness to die for their Emperor. The Japanese willingness to accept “fatality rates of 98.8 percent in the Aleutians, 99.7 percent at Tarawa, 98.4 percent at Kwajalein, and 97 percent on Saipan” forced the United Stated to take a closer look at invading Japan.35
AMERICA’S OPTIONS IN DEFEATING THE JAPANESE EMPIREPresident Harry S. Truman took office on April 12, 1945, following the death of President Roosevelt. The desperate struggle with the Japanese Empire continued with no end in sight, while the war with Nazi Germany was coming to a victorious close. After the war in Europe ended on May 8, 1945, U.S. military leaders focused their planning efforts and available resources on the swift defeat of Japan. To force the Japanese to accept unconditional surrender, senior U.S military and civilian leaders needed just to agree on how to defeat Japan. They discussed several options, including an intensification of the naval blockade and aerial bombardment of the Japanese Homeland, invasion, a negotiated peace, and dropping the newly developed atomic bomb. In order to accomplish any of the options, the United States had to tighten the naval blockade and sustain the continuous aerial bombardment campaign of the Japanese Homeland.
The United States had been planning for a possible conflict with Japan since 1905, after the Japanese defeated the Russians in the Russo-Japanese War. American planners had developed a series of contingency plans for conflicts with all wars against potential enemies, not just Japan. Each plan referred to countries by a designated color: red for Great Britain, black for Germany, green for Mexico, and orange for Japan. The early version of the “Orange Plan” assumed that Japan would invade the Philippines, a vital location for a U.S. naval base for any offensive campaign against Japan. However, army and navy leaders could not agree on how to defend the Philippines. The Army wanted the defendable Manila Bay as a base; the navy preferred Olongapo located on Subic Bay, for its easy access to an invading fleet, and did not want the American fleet “bottled up” in Manila Bay. The navy in the end chose Pearl Harbor as its primary base in the Pacific, while the army continued to fortify Manila Bay. To make the situation worse, the U.S. Congress would not allocate funding for bases in the Philippines.1 After years of debates and revisions, U.S. military planners in 1924 officially accepted a version of the Orange Plan, which called for bases in the Philippines, a “decisive naval battle” with the Imperial Navy, a naval blockade of the Japanese Homeland, interdiction of Japanese trade with China and the East Indies, and forcing the Japanese Government into negotiations.
The Orange Plan did not call for an invasion of Japan. With the development of land-based aircraft, later versions addressed the need to recapture vital islands “to prevent their use by the Japanese as air bases” against the American fleet. On December 7, 1941, the Japanese made America’s strategy of defeating Japan vastly more difficult to implement. The Japanese conquered all the islands the United States needed to execute War Plan Orange and crippled the fleet tasked to defeat the Imperial Navy and to blockade Japan.2 The strategy of defeating Japan through a naval blockade and strategic bombing was not a new concept; it was the basis of the previous Orange Plan and later Rainbow Plan. The primary advocates of this strategy were Admiral Ernest J. King, Commander in Chief of the U.S.
Fleet, and Admiral William D. Leahy, Chief of Staff to the President. Both men believed that the United States could force Japan to “accept our terms merely by our suffocating naval blockade and our devastating air assault.”3 The Japanese cities were already under intense aerial bombardment and American submarines were sinking Japanese shipping at will, which denied Japan of vital war-making materials and food for its population. By the summer of 1945, the Ronald H. Spector, Eagle Against the Sun, pp. 54 - 55.
Thomas B. Allen, Codename Downfall: The Secret Plan o Invade Japan and Why Truman Dropped the Bomb, pp. 23 – 24.
Herbert Feis, Japan Subdued: The Atomic Bomb and the End of the War in the Pacific, p. 5.
United States was in a better position to intensify both the blockade of the Japanese home islands and the bombing of Japanese cities from recently conquered islands.
After the Japanese attack on Pearl Harbor, the United States did not have the naval or air forces available to blockade Japan effectively. Furthermore, the American submarine fleet was not in any condition to wage war on Japan. On December 7, a few hours after the Japanese attack ended, President Roosevelt authorized the use of unrestrictived submarine warfare against Japanese merchant shipping. His decision ended the international agreement the United States, Britain, and Japan had signed at the London disarmament conference of 1930. At the conference, all parties agreed that submarines, “may not sink, or render incapable of navigation, a merchant vessel without having first placed passengers, crew and ship’s papers in a place of safety.”4 American naval doctrine prior to World War II centered on deploying submarines as scouts, ambushers, and as a first-line of defense against an enemy fleet, but not as lone hunters hunting unarmed merchant ships. American submarine warfare in 1942 produced disappointing results. Not only did the U.S. submarine fleet fail to influence the Japanese invasion of the Philippines, but also it sank only 180 Japanese ships totaling 725,000 tons. Since U.S.
submarines were not targeting merchant ships, the Japanese overcame those losses and even increased their tanker fleet. The U.S. Navy changed tactics in 1943 to concentrating more on tankers and other merchant ships and less on the capital warships, a shift that took an increasing toll on Japan’s oil imports and disrupted its ability to reinforce isolated island garrisons. By the end of 1944, two-thirds of Japan’s tanker fleet and half of its merchant fleet were lost to U.S.
submarines and bulk imports to the home islands were down to 40 percent.5 Spector, Eagle, p. 479.
Ibid., pp. 480 – 487.