Recent defeats and the steady bombing of Tokyo were wearing heavily on Japan. Then, atomic bombs dropped on Hiroshima and Nagasaki hastened the end of World War II. Had that not happened 50 years ago this month, an elaborate U.S. invasion plan was in place. Based on casualty estimates, the Army ordered 370,000 Purple Hearts.
In 1945 the United States began planning a massive assault on the Japanese home islands. Beginning on 1 November, an assault force of 14 U.S. Army and Marine divisions was designated to storm ashore on Kyushu, the southernmost of the home islands, in Operation Olympic.
And if Japan did not surrender, an even larger invasion of the main island of Honshu would begin in March 1946—Operation Coronet. Those would have been the largest amphibious landings of the war—much more massive than the Normandy D-Day landings. The Kyushu invasion and, if necessary, the assault on Honshu in spring 1946, would have been the bloodiest battles of World War II.
The U.S. assault on Okinawa from April to June 1945 was to be the penultimate campaign of World War II, prelude to the final battle of the Japanese home islands. Many U.S. commanders believed that it would be a model for the invasion of Japan. The main island of the Ryukyu chain, Okinawa was only 350 miles southwest of Kyushu, within range of fighter aircraft based there. The island was Japanese territory, and the Okinawans were Japanese citizens, unlike the conquered peoples encountered in most previous Pacific assaults.
Thus, the natives fought with tenacity. At Okinawa the equivalent of fewer than three Japanese divisions, with no possibility of relief or victory, heavily pounded by U.S. aircraft and naval bombardment, had held out for more than 100 days against a larger U.S. ground force with massive close air support. Both sides suffered horrendous casualties. Even as the Battle for Okinawa was raging, evidence began to surface that the battle for the home islands would be even more savage.
The U.S. decoding of Japanese communications—the Top Secret Ultra-Magic effort—indicated Japan’s preparations for the U.S. invasion: As Germany was about to fall, for example, the Japanese Army General Staff sent a message to the Japanese military attaché in Lisbon, Portugal, asking that the “battle of resistance” in Germany “be reported as fully as possible in order to furnish reference material for the decisive battle in our homeland and particularly for the training of special guard units and citizens’ volunteer units. ... In this way, we shall make firm our determination to defend the capital to the bitter end.” Magic was also intercepting diplomatic traffic originating in Japan from representatives of neutral nations, information that was coming from relatively objective eyewitnesses in Tokyo. An intercepted message from the Portuguese Minister in Japan, for instance, said that “the fortification of coasts and mountains continues, giving the impression that this country, like Germany, is disposed to prosecute the war to its very end without the least probability of victory. ... A national guard is being organized to fight as guerrillas against the invaders.”
An intercepted dispatch from the Swiss Minister in Tokyo said that Japan “is still hoping to escape [defeat] by prolonging the war long enough to exhaust [its] enemies. Many eagerly desire the landing of the Americans in Japan proper, since they think it would be the last chance to inflict upon the Americans a defeat serious enough to make them come to terms.”1
On 14 June, Fleet Admiral William D. Leahy, Chief of Staff to President Harry S. Truman, sent a memo to the Joint Chiefs of Staff saying that the President wanted to meet with them on 18 June “to discuss details of our campaign against Japan.” Truman, Leahy said, “expects at this meeting to be thoroughly informed of our intentions and prospects in preparation for his discussions with Churchill and Stalin.”
Truman’s intention, Leahy wrote, was “to make his decisions on the campaign with the purpose of economizing to the maximum extent possible in the loss of American lives. Economy in the use of time and in money cost is comparatively unimportant.”
For the 18 June meeting of the Joint Chiefs of Staff, General of the Army Douglas A. MacArthur, who would command the landings in Japan, sent his casualty estimates: a total of 95,000—dead and wounded—for the expected 90-day campaign to seize the southern half of Kyushu.
“The foregoing,” MacArthur said, “are estimated total battle casualties from which estimated return to duty numbers are deducted. Not included in the foregoing are non battle casualties which are estimated at 4200 for each 30 day period.”2
General of the Army George C. Marshall, the Army Chief of Staff, was not satisfied. A few hours before the scheduled meeting, he sent another message to MacArthur:
The President is very much concerned as to the number of casualties we will receive in the Olympic operation. This will be discussed with the President about 3:30 PM today Washington time. Is the estimate given in your [message] of 50,800 for the period of D to D+30 based on plans for medical installations to be established or is it your best estimate of the casualties you anticipate from the operational viewpoint. Please rush answer.3
MacArthur apparently only then appreciated the extreme importance that the casualty rates would play in Truman’s decision about the invasion. In his long reply, he back- pedaled from his original estimate, saying it had been “a routine report. . . for medical and replacement planning purposes.”
. . . The estimate is purely academic and routine and was made for planning alone. It had not come to my prior attention. I do not anticipate such a high rate of loss. I believe the operation presents less hazards of excessive loss than any other that has been suggested and that its decisive effect will eventually save lives by eliminating wasteful operations of a nondecisive character. I regard the operation as the most economical one in effort and lives that is possible. In this respect it must be remembered that the several preceding months will involve practically no losses in ground troops and that sooner or later a decisive ground attack must be made. The hazard and loss will be greatly lessened if an attack is launched [by the Soviets] from Siberia sufficiently ahead of our target date to commit the enemy to major combat. I most earnestly recommend no change in Olympic. Additional subsidiary attacks will simply build up our final total casualties.4
Two other documents pertaining to the casualty estimates were prepared for Truman. One put the casualties as high as 220,000; the other said casualties would be closer to those suffered in the invasion of Luzon—31,000. It was a remarkable discrepancy, and exactly what Truman would believe depended upon which of two prepared briefing papers he actually adopted.
Both top secret documents were entitled “Memorandum for the President Subject: Campaign against Japan.” The first one, dated 15 June 1945, and subtitled “Details of the Campaign against Japan,” was prepared by the Joint War Plans Committee, which, in a covering memo, “recommends that the enclosed memorandum be presented to the President at his conference with the Joint Chiefs of Staff, scheduled for 18 June. The covering memo went on to say that the committee “has assumed that the questions brought up by the President will be answered and discussed orally at the conference, and that the purpose of the memorandum is for the President to have available an aide memoire which he could examine at his convenience and possibly use at the forthcoming tripartite conferences [a reference to the Potsdam Conference].” The second document, also subtitled “Details of the Campaign against Japan” but originating with the Joint Chiefs of Staff, was dated 11 July—five days before the Potsdam Conference, which most of the Joint Chiefs attended.
A paraphrase of General MacArthur’s comments on the Kyushu operation (taken almost verbatim from his message to Marshall) repeated his recommendation that “no change in the operation” be made for the invasion of southern Kyushu. It also advocated the plan to invade Honshu and the Tokyo Plain.
The difference between the two casualty tables was astonishing. The first used broad experience and objective criteria as its guide. The second blatantly reflected MacArthur’s view of casualties as merely a U.S.-to-Japanese kill ratio. The table also gratuitously included a reference to D-Day casualties at Normandy—a reflection of one of MacArthur’s perennial criticisms: Allied conduct of the European War. The second memo also showed that MacArthur—or at least MacArthuresque thinking— had already taken over the paper-pushing aspect of the invasion.
Of the many sets of numbers and arguments that would be presented to the President, the most honest were those that MacArthur gave in response to Marshall’s original message of 16 June. In it, MacArthur estimated that in the landing and three months of fighting on Kyushu, 94,250 men would be killed or wounded in battle, and another 12,600 would be felled by disease and accidents—a casualty total of 106,850.
The 15 June Joint War Plans Committee (JWPC) memo offered three scenarios and three sets of casualty estimates. If the Olympic-Coronet plan went according to schedule, two landings would take place; together, they were expected to yield 193,500 battle casualties. If, as some planners believed, the Kyushu invasion ended the war, then the battle casualty count would be 132,500. The worst- ease scenario envisioned three major amphibious assaults and the estimated consequence to be 220,000 battle casualties. To all of these figures must be added the nonbattle casualties of accidents and disease. In that case, total casualties, in the triple-invasion scenario, would exceed 250,000 and might approach 500,000.
The casualty question haunted Truman as he considered his next moves in the war against Japan. In his view, he had only two choices: He could authorize the invasion or order the use of the atomic bomb, which, he knew, was nearing reality. And if the bomb failed or was delayed, then invasion was still an option. The casualty estimates from his military advisers would influence his decision Profoundly. Simply put, low estimates would give Mac Arthur and Marshall the invasion they and other Army leaders wanted. High estimates would make the invasion a far less attractive alternative to the bomb.
Navy leaders, mindful of the heavy toll kamikazes took °n their ships at Leyte and Okinawa, tended toward pessimistic forecasts about the invasion. Leahy foresaw Okinawa-size casualty lists. Fleet Admiral Chester Nimitz, in a memo to Fleet Admiral Ernest J. King, Commander-in-Chief, U.S. Fleet, had said, “We must be prepared to accept heavy casualties whenever we invade Japan. Our Previous successes against ill-fed and poorly supplied units, cut down by our overpowering naval and air action, should not be used as sole basis of estimating the type of resistance we will meet in the Japanese homeland where the enemy lines of communication will be short and the enemy supplies more adequate.”5
Truman had stated his bomb-or-invade view in his diary on 17 June: “I have to decide Japanese strategy—shall we invade Japan proper or shall we bomb and blockade?” He seemed to have been referring to conventional aerial bombardment, but he also had to make a decision about S-1 (the code name for the atomic bomb, which, of course, he did not mention in his diary).
At 1530 on 18 June, Truman presided over the Japanese strategy meeting that he had requested through Admiral Leahy. Attending were Admiral Leahy, General Marshall, Admiral King, Secretary of War Henry Stimson, Navy Secretary James Forrestal, Assistant Secretary of War John J. McCloy, Lieutenant General Ira C. Eaker (representing the ailing General of the Army H. H. Arnold, head of the Army Air Forces), and Brigadier General A. J. McFarland, secretary to the JCS.6
Marshall opened the meeting by saying, according to the edited minutes, that “the present situation . . . was practically identical with the situation which had existed in connection with the operations against Normandy.”7 He then read, “as an expression of his views,” a memorandum prepared by the Joint Chiefs of Staff for the President strongly urging that the invasion of Kyushu proceed as planned. “General MacArthur and Admiral Nimitz are in agreement” with the plan, the memo said.
As the group discussed casualties, Marshall told the President, “It is a grim fact that there is not an easy, bloodless way to victory in war, and it is the thankless task of the leaders to maintain their firm outward front which holds the resolution of their subordinates.” The invasion of Japan, he continued, “would be difficult but not more so than the assault in Normandy.” The original minutes quoted Marshall as saying that everyone going to the Pacific should be filled with the determination to see the plan through. This was later edited to read “should be indoctrinated with a firm determination to see it through.” (Several penciled-in changes were in the original minutes. A second, smooth copy was prepared, and it became the official minutes.)
Admiral Leahy spoke up to say that the President was “interested in knowing what the price in casualties for Kyushu would be and whether or not that price could be paid. Leahy also wanted to know how many troops would be used on Kyushu. (Stricken from the minutes was what had been the rest of Leahy’s sentence: “with a view to determining therefrom the number of casualties which might be expected.”) Leahy “pointed out that the troops on Okinawa had lost 35 percent in casualties.” He apparently based his figure on the casualties as then known. The final U.S. toll at Okinawa was 7,613 killed and 31,807 wounded, a total Army-Marine-Navy casualty toll ashore of 39,420. The assault force numbered about 100,000. So the actual casualty rate was more than 39%.
Admiral King assured Admiral Leahy that Kyushu would be different from Okinawa, because the only way to attack Okinawa was by “a straight frontal attack against a highly fortified position,” while on Kyushu, “landings would be made on three fronts simultaneously and there would be much more room for maneuver. It was his opinion that a realistic casualty figure for Kyushu would lie somewhere between the number experienced by General MacArthur in the operations on Luzon and the Okinawa casualties,” or approximately 40,000 casualties.
General Marshall had just heard from General MacArthur himself that the “total force involved” was estimated as 681,000 with “one half engaged the first 15 days” for the landings, almost exactly the 340,600 figure. Using Leahy’s 35% estimate on MacArthur’s 681,000 would mean that 238,350 Americans would be killed or wounded in battle. Using Marshall’s 766,700 figure, the theoretical casualty estimate would be that much higher. No one pursued this arithmetic at the meeting, although the impression may have been left that U.S. casualties might reach as high as a quarter of a million.
President Truman continued the discussion of casualties at Potsdam in July 1945. After learning details of the success of the atomic bomb test at Alamogordo, New Mexico, he met with his principal advisers—Stimson, Byrnes, Leahy, King, Marshall, and Arnold—on 22 July.8 Apparently at this meeting, Truman wrote, "I asked General Marshall what it would cost in lives to land on the Tokyo plain and other places in Japan. It was his opinion that such an invasion would cost at a minimum one quarter of a million casualties, and might cost as much as a million, on the American side alone, with an equal number of the enemy. The other military and naval men present agreed. . . .”9
Arnold opposed the bomb, pointing out to Truman and others that Japan could be bombed into submission by B-29 attacks using incendiaries. “But none of the other military men—especially General Marshall—concurred with General Arnold. Anyway, my father saw that conventional bombing, even if it worked—and no one doubted that it might take months, even a year—would cause more Japanese deaths than the use of one or two atomic bombs, wrote Truman’s daughter, in an insightful biography of her father.10 This latest estimate of casualties added to Truman’s growing conviction about the need to use the bomb.
Thus, no simple answer exists to the question: How many would have died” if the war continued with U.S. landings on Kyushu, possibly followed by an assault on the main island of Honshu.
Truman’s memoirs say that General Marshall had told him an invasion of Japan “would cost at a minimum one quarter of a million casualties, and might cost as much as a million, on the American side alone, with an equal number of the enemy.” Secretary of War Stimson made a similar estimate in a postwar memoir. The numbers that General MacArthur submitted to General Marshall for the crucial 18 June White House meeting were well below Truman’s recollection of Marshall’s estimates.
For whatever reason, MacArthur’s figures were unrealistic. But far more important is what MacArthur s own intelligence officers discovered after the war. From interrogations of high ranking Japanese staff officers, MacArthur’s O-2 staff reported:
The strategists at Imperial General Headquarters believed that, if they could succeed in inflicting unacceptable losses on the United States in the Kyushu operation, convince the American people of the huge sacrifices involved in an amphibious invasion of Japan, and make them aware of the determined fighting spirit of the Japanese army and civilian population, they might be able to postpone, if not escape altogether, a crucial battle in the Kanto [Tokyo] area. In this way, they hoped to gain time and grasp an opportunity which would lead to the termination of hostility on more favorable terms than those which unconditional surrender offered.11
The summons to the decisive battle was not just a patriotic shout. It was a strategy.
As the date for Operation Olympic approached, two U.S. Army agencies made independent estimates of invasion casualties. The Philadelphia Quartermaster Depot— which procured everything from combat boots to medals for the Army—ordered more than 370,000 Purple Hearts, expected to be awarded after the final battles for Japan.12
At the same time, on Luzon, the Sixth Army’s medical staff estimated that casualties from the Kyushu assault and subsequent fighting to secure the southern half of the island would cost 394,000 Americans dead, wounded, and missing.13 At Okinawa—in a battle that proffered many similarities to the fighting on Kyushu—the Tenth Army suffered 7,613 soldiers and Marines killed and missing and 31,807 wounded. Using that same 1-to-4 ratio for the Kyushu battles, the Sixth Army could expect some 98,500 dead and 295,500 wounded.
Also using Okinawa as a model, where 4,907 U.S. Navy men were killed on board ships and 4,824 wounded, the Kyushu assault in the face of heavy air and undersea kamikaze attacks could have similarly inflicted ten times the number of naval casualties—on the order of 49,000 Navy men and troops on board ships killed and 48,000 wounded.
Thus, a reasonable casualty estimate of the Kyushu assault—based on medical staff estimates and not influenced by the politics of Mac Arthur’s headquarters or Washington—could have been on the order of 147,500 dead and 343,000 wounded. While these numbers are of a higher magnitude than those developed by Mac Arthur’s headquarters for President Truman’s meeting with the Joint Chiefs of Staff, the estimates were developed by medical specialists experienced in battle, men who had to be ready with blood and plasma, medical personnel, and evacuation spaces on ships. Even allowing a contingency margin, the Sixth Army’s estimates must be taken seriously. Kyushu would have been the bloodiest invasion in history. And it could have been surpassed by the assault of Honshu, which was planned to follow if the Japanese did not surrender by spring 1946.
Had the invasions occurred, they would have been the most savage battles of the war. Thousands of young U.S. military men and perhaps millions of Japanese soldiers and civilians would have died. Terror weapons could have scarred the land and made the end of the war an Armageddon even worse than the devastation caused by two atomic bombs.
A third atomic bomb would have been ready to drop on Japan before the end of August, and another Japanese city would probably have been the target. More atomic bombs were in production. And from what is now known about Marshall’s thinking on the tactical use of atomic bombs, the plans for Operation Downfall would have been modified to include the use of atomic bombs in direct support of the landings. Strong proposals also came from U.S. commanders to employ poison gas, crop-killing chemicals, and even biological weapons against the Japanese in an effort to hold down casualties. The devastation of Japan could have been total.14
And U.S. casualties in the invasion—or invasions— of Japan would have certainly been in the hundreds of thousands.
1 Magic Summary No. 1188, 26 June 1945, SRS 1710.
2 Gen. MacArthur message to Gen. Marshall from CinCAFPac to WarCOS, 17 June 1945, WD 1052 (MacArthur Archives).
3 Gen. Marshall message to Gen. MacArthur are from Gen. Marshall to Gen. MacArthur (Personal) 19 June 1945, WD 1056 (MacArthur Archives). The 19 June date appears twice on the message, even though the meeting Marshall refers to is 18 June.
4 Gen. MacArthur to Gen. Marshall (Personal) C-19848, 19 June 1945, WD 1057 (MacArthur Archives).
5 Ronald H. Spector, Eagle Against the Sun (New York: The Free Press, 1985), p544. The memorandum is dated 28 April 1945.
6 Attendance at meeting from Truman Library, President Secretary’s Files.
7 Minutes of meeting held at the White House on Monday, 18 June 1945, at 1530 (National Archives).
8 There is confusion among the Potsdam accounts as to precisely when this meeting was held and who attended. See Margaret Truman, Harry S. Truman (New York: Morrow, 1973), pp. 273-274; and Foreign Relations of the United States: The Conference of Berlin (The Potsdam Conference), 1945, Vol. II, 243. Churchill joined Truman and his advisers at the end of this meeting (Winston Churchill, Triumph and Tragedy [New York: Houghton Mifflin, 1986], p. 638).
9 Truman letter to James Lea Cate, 12 January 1953, reproduced in Craven and Cate, The Pacific: Matterhorn to Nagasaki (Washington, D.C.: Office of the Air Force, 1953), between pages 712 and 713.
10 Arnold’s views are in Margaret Truman, 273.
11 Reports of General MacArthur, Vol. I, 418. The interrogated officers were LGen. Seizo Arisue and LGen. Torashiro Kawabe, deputy chief, Army General Staff.
12 Lt. David L. Riley, USN, in Uncommon Valor. . . Decorations, Badges and Service Medals of the U.S. Navy and Marine Corps (Hopkinsville, KY: [Privately printed], 1980), p. 3. Riley noted that “several hundred thousand” Purple Hearts were manufactured near the end of the war in anticipation of the invasion. It was from this World War II stock that medals were awarded in the Korean, Vietnam, and Persian Gulf wars and in all combat incidents since August 1945. The Air Force Association used this information as a gauge for estimating invasion casualties (The Washington Post, 26 September 1994). The public affairs office at the Defense Personnel Support Center (successor to the Philadelphia Quartermaster Depot) has stated that records showing the exact size and date of the order could not be found but that the size is such that all Purple Hearts awarded since the end of World War II came from that final order; an unknown number are still in storage. More than 370,000 Purple Hearts have been awarded since 1945.
13 U.S. Sixth Army, “Medical Service in the Asiatic and Pacific Theaters,” unpublished manuscript, Chapter XV (U.S. Army Center of Military History).
14 Marshall’s view of tactical atomic bombs is in Barton J. Bernstein, “Eclipsed by Hiroshima and Nagasaki: Early Thinking About Tactical Nuclear Weapons,” International Security, (Spring 1991), p. 168.
Mr. Polmar and Mr. Allen have collaborated on six books, the most recent of which is the new Code-Name Downfall: The Secret Plan to Invade Japan and Why Truman Dropped the Bomb (New York: Simon and Schuster, 1995).
The Best Estimate
The two top-secret documents prepared for President Harry S. Truman relating to casualty projections for an invasion of Japan were almost identical, as they went through sections labeled Strategy, Presently planned campaign, Forces required for presently planned campaign. Then came the section labeled Casualties.
The 15 June memorandum said:
Casualties. The cost in casualties of the main operations against Japan are not subject to accurate estimate. The scale of Japanese resistance in the past has not been predictable. Casualty expectancy rates based on experience in the Pacific vary greatly from the short bloody battle of Tarawa to the unopposed landing at Lingayen (Luzon). It would be difficult to predict whether Jap resistance on Kyushu would more closely resemble the fighting on Okinawa or whether it would parallel the battle of Leyte. Certain general conclusions can, however, be reached. The highest casualty rate occurs during the assault phase of an amphibious operation; casualties in land warfare are a function of the length of the campaign and of the scale of opposition encountered. Naval casualties can be expected to vary directly with the number of amphibious operations involved and with the length of the campaign. Casualties can be kept to a minimum, then, by terminating the war at the earliest possible time by means of the fewest possible assault operations and by conducting land campaigns only in decisive areas. The presently planned campaign, which involves two assault operations followed by land campaigns in the Japanese homeland, is in conformity with this principle. Further, the extent of the objective area gives us an opportunity to effect surprise as to the points of landing and, once ashore, to profit by our superiority in mobility and mechanized power through maneuver. Should it be decided to follow the southern Kyushu operation by another operation such as against northern Kyushu in order to exploit bombardment and blockade, and should this bring about capitulation of the Japanese, the casualties should be less than for the presently planned campaign. We consider that at this time it would be a pure gamble that the Japanese would admit defeat under such conditions. If they do not, invasion of the Tokyo Plain might still be required with resultant increased total casualties.
The best estimate of casualties for these possible sequences of operations follows. For the reasons stated above, it is admittedly only an “educated guess.” (See Figure 1.)
The 11 July memorandum, which would be the basis for Pacific War strategy discussion at Potsdam, had a drastically different casualty prediction. And instead of preceding the estimates with a long, thoughtful explanation of how the estimates were made, the memorandum said, merely:
Casualties. Our casualty experience in the Pacific war has been so diverse as to throw serious doubt on the validity of any quantitative estimate of casualties for future operations. The following data indicate results of experience.* (See Figure 2.)
After the table, still under the Casualties heading, were these paragraphs:
The record of General Mac Arthur’s operations from 1 March 1944 through 1 May 1945 shows 13,742 U.S. killed compared to 310,165 Japanese killed, or a ratio of 22 to 1. During this same period, the total U.S. casualties, killed, wounded and missing, were 63,510 or a ratio of approximately 5 to 1.
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 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.
*This is the first time Navy casualties are mentioned. At Okinawa, more than 4,900 Navy men were killed and almost that many wounded.