"We hated the Japs but nobody had the slightest desire to go there and fight them because the one thing we knew was that we'd all be killed. I mean we really knew it. I never used to think that, I used to say the Japs would never get me. But there was no question about the mainland. How the hell are you going to storm a country where women and children, everybody would be fighting you? Of course we'd have won eventually but I don't think anybody who hasn't actually seen the Japanese fight can have any idea of what it would have cost."
- Austin Aria, veteran of the Okinawa campaign.
Intelligence Success or Failure?
The U.S. intelligence estimates of July 1945 were alarming to Olympic planners. They warned that the build-up of Japanese forces in southern Kyushu was reducing the U.S. attack force ratio of 3:1 to 1:1. In fact, the Japanese by this time had surpassed the 1:1 ratio and actually outnumbered the American invasion force. In July 1945, the U.S. intelligence estimates were underestimating Japanese strength on Kyushu by about 36 percent! To make matters worse, General MacArthur, based on previous operations in the Pacific, believed that U.S. intelligence typically overestimated Japanese strength. MacArthur downplayed his own staff's casualty estimates and told General Marshall that he "regarded the operation (Olympic) as the most economical one in effort and lives that is possible."(1)
The underestimation of Japanese forces resulted from the continuous movement of Japanese forces into Kyushu throughout the spring and early summer of 1945. Because Kyushu was not an isolated island far out in the Pacific and with the situation changing daily, U.S. intelligence found it difficult to be 100 percent accurate on Japanese strength. Reconnaissance flights over the landing beaches on Kyushu were sporadic, because the main effort of the Strategic Air Forces during the spring of 1945 was the bombing campaign of the Japanese cities. When reconnaissance flights were flown in support of Olympic planning, photo analysts were presented with a continually changing ground situation. Communications intercepts were the best method of identifying Japanese ground units in Kyushu. However, it took time to identify Japanese units by piecing together the intercepted message traffic.
By 1 August 1945, almost all of the Japanese forces that were to defend Kyushu were in place. As the 1 November invasion date approached, reconnaissance flights would have increased and, with Japanese forces remaining static, the intelligence picture should have become clearer. Also, communications intercept analysts would have had more intercepted traffic from which to identify all the Japanese units on Kyushu. By October, U.S. forces would probably have identified the majority of Japanese units in Kyushu and correctly assessed their defensive preparations and capabilities. This would have led to either the postponement of Operation Olympic, an increase in the size of the invasion force, or possibly the use of atomic bombs in support of an invasion to destroy Japanese military forces on Kyushu.
At the strategic level, there was an incomplete intelligence picture based on faulty analysis. MacArthur and the Joint Chiefs of Staff believed that the Japanese would not commit all of their resources in the battle for Kyushu; they assumed that the Japanese would husband their assets, especially aircraft, for the battle for Tokyo. They failed to assess the Japanese' intention to fight a decisive final battle on Kyushu. There was also a lack of understanding about the operational situation on Kyushu. In a Memorandum for the President, Details of the Campaign Against Japan, dated 15 June 1945, the Joint War Plans Committee wrote, "The extent of the objective area gives us the opportunity to effect surprises at the points of landing and, once ashore, to profit by our superiority in mobility and mechanized power through maneuver."(2)
This statement was used in an attempt to differentiate Olympic and Coronet from the bloody island battles in the Pacific. However, the statement could not have been further from reality. The Japanese had determined the location and time of the invasion, and certainly the terrain would have restricted the mobility and maneuver capability of the U.S. forces. At the tactical level, analysis of Japanese capabilities and intentions was extremely accurate. The Sixth Army G-2 correctly assessed that the battle for Kyushu was to be the Japanese decisive battle of the war, and that there would be no husbanding of Japanese forces. The Sixth Army G-2 also was the only one to correctly assess the Japanese operational tactic of attempting to defeat the American forces at the beach. General MacArthur's staff and the JCS planners believed that the Japanese would not defend the beach, preferring to defend inland, similar to what was seen at Okinawa and the Philippines.
The major failure of intelligence concerned the Japanese capability for suicide attacks. In spite of countermeasures, the suicide attacks directed against the U.S. task forces and transport areas would unquestionably have been serious and would have caused severe losses. The kamikaze attacks against the U.S. fleet at Okinawa came after the aircraft flew more than 500 miles over open ocean. Many inexperienced pilots lost their way and never reached the American fleet. This great distance also allowed the fleet to receive early warning from picket ships and scramble fighters to engage the kamikazes. Bad weather in the target area also hampered the kamikaze pilots from acquiring their targets. With all of these difficulties, the Japanese ratio of planes launched to planes successfully striking their targets was 1 in 9. The Japanese flew 1,840 "special-attack" planes during the battle for Okinawa. A ratio of 1 in 9 would equate to approximately 202 planes striking their targets.(3) The U.S. Navy reported 192 ships hit by kamikaze planes during the battle of Okinawa; of these, 15 were sunk.
Although the damage inflicted by the Kamikaze planes was superficial, they managed to kill 12,300 American servicemen and wound 36,400. For the defense of Kyushu the Japanese were to employ upwards of 10,000 kamikaze planes. Although the Japanese staff planned for a hit ratio of 1 in 9, many believed that they would be far more successful. The special attack aircraft would have to fly less than 100 miles to their target with almost the entire distance spent over land masked by terrain. The U.S. fleet would have very little warning time to intercept the aircraft. Anchored troop transports, just off the coast, would be easy targets as they unloaded their cargo. It is highly probable that the Japanese suicide attack hit ratio would have been higher, probably closer to 1 in 6 or
1 in 7. At these ratios, 1,400 to 1,600 kamikaze aircraft would have hit American ships. With their targets being transports, the casualty rate per hit would have been higher than at Okinawa where destroyers were the primary target. In addition to the kamikaze aircraft, the U.S. fleet also would have had to deal with all of the Japanese Navy's special attack boats and midget submarines. Even if the suicide attacks were only marginally successful, the U.S. attack ratio would have eroded still farther. If the Japanese did succeed in delivering 1,500 hits against the transports, the mythical "Divine Wind" may well have blown again, turning away another invasion fleet.
V Amphibious Corps
The landing of V Amphibious Corps on the western beaches of Satsuma peninsula was faced with a series of complex difficulties. The ridge running parallel to the relatively narrow landing beaches offered some defilade for the Japanese coastal defenders. In the battle for Okinawa, despite the heaviest bombardment in a Pacific campaign, only civilian buildings had been demolished; the defense works at the beaches were virtually intact. Their generally excellent condition testified to the unrealistic American value placed on massed naval gunfire and air bombardment, as well as to the Japanese skill in choosing and fortifying sites.(4) On Okinawa the Japanese had six months to position caves, gun emplacements and pillboxes. On Kyushu, with a greater supply of materials, the Japanese had seven months to prepare defensive positions before the invasion.(5)
The Second and Third Marine Divisions would each assault across a beach south of Kushikino. Each beach that the divisions were to assault was defended by one Japanese battalion from the 303rd Division. The mountainous, rough terrain inland from the beach provided advantageous sites for observation, emplacement of weapons and for cover and concealment. The terrain favored the defender. Neither side had the opportunity for maneuver. The Japanese had the advantage of the choice of sites for defensive weapons and troop disposition. They had excellent observation of the landing beaches and any advance inland.
The Second Marine Division, to the right of the Third Marine Division, would have had more open terrain to their front and right after crossing the initial ridge. However, the open country was marshy, full of rice paddies, and reasonably short of cover and concealment. Sufficient high ground surrounding the open terrain afforded the Japanese with continual observation and the ability for mutually supporting defensive fires. As Second Marine Division pushed to Kagoshima, its ever expanding right flank would become vulnerable to the Japanese 206th and 146th Divisions, and the 125th IMB located to the south. When the Japanese 40th Army determined that the landing in the vicinity of Kushikino was the main effort on the peninsula, then, per orders, the Japanese forces would have converged on the VAC beachhead. The Japanese forces would have arrived piecemeal and under continuous air attack with the mission to establish defensive positions to contain the beachhead in order to set up the decisive counterattack. With a short distance to travel amidst cover and concealment in the mountainous terrain, the Japanese forces probably would have set up defensive positions in the hills before the Marine divisions could break out of their beachhead. Second Marine Division would have had to fight its way through elements of two Japanese divisions to reach Kagoshima only to face a counterattack by the 77th Division, considered one of the best on Kyushu.
To the north, the Third Marine Division would have had a rough time forcing the narrow and difficult corridor to their objective, the town of Sendai. Third Marine Division would have been up against the remnants of the 303rd Division. Although not a top line unit, the 303rd Division would have benefited from very restricted terrain. The battle would have been infantry against infantry. U.S. superiority in firepower and mobility would have had little effect on the dug-in Japanese.
While many of the Japanese troops were ill-trained and ill-equipped compared to U.S. standards, they were prepared to die for their homeland. One need only to look at Peleliu, Iwo Jima and Okinawa to see a prelude of what was going to occur. For example, at Iwo Jima the 22,000 defenders were a hodgepodge of airman, unhappy sailors serving as infantrymen, and ill-trained, "second string" Army units. After his first inspection of the island's defenses and the men who would man them, General Kuribayashi, the Commanding General, told his aide, "these are no soldiers, just poor recruits who don't know anything. Their officers are superannuated fools. We cannot fight the Americans with them."(6) But fight they did, going up against the Third, Fourth and Fifth Marine Divisions and inflicting more casualties than they received. On Kyushu, the V Amphibious Corps would likely have expended itself trying to reach its two primary objectives, Sendai to the north and Kagoshima to the east.
On 18 July 1945, the Joint War Plans Committee issued another Memorandum for the President to assist Truman in preparing for the Potsdam Conference. This memorandum again highlights the misunderstanding of the situation on Kyushu at the strategic level. It claimed, "the nature of the objective area in Kyushu gives maneuver room for land and sea operations. For these and other reasons it is probable that the ground cost in ground force casualties for the first 30 days of the Kyushu operation will be on the order of that for Luzon. Naval casualties will probably be at about the same rate as for Okinawa."(7) To determine a projected casualty rate for Operation Olympic an examination of the experiences of fighting the Japanese throughout the war is necessary. Following is a chart which shows the casualty rates of six battles which occurred during the last 12 months of the war in the Pacific.
Based on the terrain and the Japanese defensive preparations and strategy, the battle for Kyushu would have resembled the battles of the central Pacific instead of the campaigns in the Philippines. With the casualty ratios of those battles applied to Operation Olympic, the estimate for U.S. casualties would have been 94,000 killed and 234,000 wounded.(8) The total casualty estimate of 328,000 equates to 57 percent of the U.S. ground forces slated for Olympic. On the Satsuma Peninsula, the V Amphibious Corps casualty estimate would have been 13,000 killed and 34,000 wounded, or approximately 54 percent of the Marine force. This casualty estimate for VAC is made without any additional Japanese forces moving into the 40th Army's zone. Add to these estimates the results of kamikaze attacks against transports, and the battle for Kyushu would have been devastating to the American people.
Many historians use the casualty estimate that was briefed to Truman in June 1945 to claim that the projected low casualty rate of 25,000 dead did not justify the use of the atomic bomb. However, those casualty estimates were based on an April 1945 estimate of Japanese force strength of around 229,000. By July 1945, that force had almost tripled to 657,000. With this sizable ground force supported by the special attack forces, it is easy to reach a total casualty figure of close to 500,000 Americans. This is the same number used by Truman in later accounts in his diary to justify the use of the atomic bomb. In addition to U.S. casualties, the Japanese on Kyushu would likely have suffered upwards of 2,000,000 military and civilian casualties. These projected figures for Kyushu far exceed the casualties inflicted by the atomic bombs dropped on Hiroshima and Nagasaki, which ended the War with Japan.
General MacArthur was determined to lead the largest amphibious operation in history and General Marshall was willing to support MacArthur in this endeavor. Concerned about high casualties, President Truman had little enthusiasm for a ground invasion of the Japanese home islands. It was General Marshall that downplayed the projected casualty figures and influenced Truman to approve the operation. When intelligence estimates showed a Japanese defensive buildup, MacArthur all but ignored them, while Marshall contemplated the use of the atomic bomb in a tactical role. If Operation Olympic had been executed, as planned, on 1 November 1945, it would have been the largest bloodbath in American history. Although American forces had superior fire power and were better trained and equipped than the Japanese soldier, the close-in, fanatical combat between infantrymen would have been devastating to both sides. It is important to note that American battle deaths for the entire war numbered approximately 292,000, with another 671,000 wounded.(9)
Had not the Japanese surrendered after the dropping of the second atomic bomb on Nagasaki, Operation Olympic would most likely have been conducted in order to bring about Japan's unconditional surrender. However, by the invasion date of
1 November 1945, intelligence would have accurately identified the true nature of the Japanese defensive capability on Kyushu. New casualty estimates based on this intelligence, would likely have influenced President Truman to use the atomic bomb as a tactical weapon against the beach defenses on Kyushu. Although probably a successful tactic to defeat the Japanese on Kyushu, historian Edward Drea points out the dreadful results of such use of the atomic bomb:
"...American GIs and Marines who would have landed on radioactive beaches - another hell, that of radiation poisoning, might well have been in store. In 1945 no one really grasped the implications of radioactive fallout, and the hellish effects would undoubtedly have persisted for decades after the explosions."(10)
1. Allen and Polmar, Code-Name Downfall, 204.
2. ibid., 206.
3. Naito, Thunder Gods, The Kamikaze Pilots Tell Their Story, 182.
4. George Feifer, Tennozan: The Battle of Okinawa and the Atomic Bomb (New York: Ticknor & Fields, 1992), 145. U.S. forces did meet a determined beach defense because only two months before the invasion the Japanese defensive strategy changed and the fortifications were abandoned.
5. Department of the Army, Homeland Operations Record, Japanese Monograph Nos. 17, 18, 19, & 20, October 1945, 215. Fortification materials allotted to the Sixteenth Area Army from April to June 1945 included:
Fuel 250,000 liters
Explosives 300 Metric tons
Cement 21,200 Metric tons
Steel 1,000 Metric tons
Lumber 3,463,290 cubic feet
6. Ross, Iwo Jima Legacy of Valor, 62.
7. Allen and Polmar, Code-Name Downfall, 208.
8. The ratio used for killed in action was 1:7 and the ratio used for total casualties was 1:2. A Japanese total strength of 657,00 ground troops was used against a total strength for American ground forces of 575,000.
9. Peter Maslowski, "Truman, the Bomb, and the Numbers Game," MHQ: The Quarterly Journal of Military History, Spring 1995, Vol. 7, No. 3, 105.
10. Edward J. Drea, "Previews of Hell," MHQ: The Quarterly Journal of Military History, Spring 1995, Vol. 7, No. 3, 81.