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The Biggest Decision: Why We Had To Drop The Atomic Bomb

June 2024
15min read

Truman was Commander in Chief of the American armed forces, and he had a duty to the men under his command not shared by those sitting in moral judgment decades later

On the morning of August 6, 1945, the American B-29 Enola Gay dropped an atomic bomb on the Japanese city of Hiroshima. Three days later another B-29, Bock’s Car , released one over Nagasaki. Both caused enormous casualties and physical destruction. These two cataclysmic events have preyed upon the American conscience ever since. The furor over the Smithsonian institution’s Enola Gay exhibit and over the mushroom-cloud postage stamp last autumn are merely the most obvious examples. Harry S. Truman and other officials claimed that the bombs caused Japan to surrender, thereby avoiding a bloody invasion. Critics have accused them of at best failing to explore alternatives, at worst of using the bombs primarily to make the Soviet Union “more manageable” rather than to defeat a Japan they knew already was on the verge of capitulation.

By any rational calculation Japan was a beaten nation by the summer of 1945. Conventional bombing had reduced many of its cities to rubble, blockade had strangled its importation of vitally needed materials, and its navy had sustained such heavy losses as to be powerless to interfere with the invasion everyone knew was coming. By late June advancing American forces had completed the conquest of Okinawa, which lay only 350 miles from the southernmost Japanese home island of Kyushu. They now stood poised for the final onslaught.

Okinawa provided a preview of what an invasion of the home islands would entail. Rational calculations did not determine Japan’s position.

Rational calculations did not determine Japan’s position. Although a peace faction within the government wished to end the war—provided certain conditions were met—militants were prepared to fight on regardless of consequences. They claimed to welcome an invasion of the home islands, promising to inflict such hideous casualties that the United States would retreat from its announced policy of unconditional surrender. The militarists held effective power over the government and were capable of defying the emperor, as they had in the past, on the ground that his civilian advisers were misleading him.

Okinawa provided a preview of what invasion of the home islands would entail. Since April 1 the Japanese had fought with a ferocity that mocked any notion that their will to resist was eroding. They had inflicted nearly 50,000 casualties on the invaders, many resulting from the first large-scale use of kamikazes. They also had dispatched the superbattleship Yamato on a suicide mission to Okinawa, where, after attacking American ships offshore, it was to plunge ashore to become a huge, doomed steel fortress. Yamato was sunk shortly after leaving port, but its mission symbolized Japan’s willingness to sacrifice everything in an apparently hopeless cause.

The Japanese could be expected to defend their sacred homeland with even greater fervor, and kamikazes flying at short range promised to be even more devastating than at Okinawa. The Japanese had more than 2,000,000 troops in the home islands, were training millions of irregulars, and for some time had been conserving aircraft that might have been used to protect Japanese cities against American bombers.

Reports from Tokyo indicated that Japan meant to fight the war to a finish. On June 8 an imperial conference adopted “The Fundamental Policy to Be Followed Henceforth in the Conduct of the War,” which pledged to “prosecute the war to the bitter end in order to uphold the national polity, protect the imperial land, and accomplish the objectives for which we went to war.” Truman had no reason to believe that the proclamation meant anything other than what it said.

Against this background, while fighting on Okinawa still continued, the President had his naval chief of staff, Adm. William D. Leahy, notify the Joint Chiefs of Staff (JCS) and the Secretaries of War and Navy that a meeting would be held at the White House on June 18. The night before the conference Truman wrote in his diary that “I have to decide Japanese strategy—shall we invade Japan proper or shall we bomb and blockade? That is my hardest decision to date. But I’ll make it when I have all the facts.”

Truman met with the chiefs at three-thirty in the afternoon. Present were Army Chief of Staff Gen. George C. Marshall, Army Air Force’s Gen. Ira C. Eaker (sitting in for the Army Air Force’s chief of staff, Henry H. Arnold, who was on an inspection tour of installations in the Pacific), Navy Chief of Staff Adm. Ernest J. King, Leahy (also a member of the JCS), Secretary of the Navy James Forrestal, Secretary of War Henry L. Stimson, and Assistant Secretary of War John J. McCloy. Truman opened the meeting, then asked Marshall for his views. Marshall was the dominant figure on the JCS. He was Truman’s most trusted military adviser, as he had been President Franklin D. Roosevelt’s.

Marshall reported that the chiefs, supported by the Pacific commanders Gen. Douglas MacArthur and Adm. Chester W. Nimitz, agreed that an invasion of Kyushu “appears to be the least costly worthwhile operation following Okinawa.” Lodgment in Kyushu, he said, was necessary to make blockade and bombardment more effective and to serve as a staging area for the invasion of Japan’s main island of Honshu. The chiefs recommended a target date of November 1 for the first phase, code-named Olympic, because delay would give the Japanese more time to prepare and because bad weather might postpone the invasion “and hence the end of the war” for up to six months. Marshall said that in his opinion, Olympic was “the only course to pursue.” The chiefs also proposed that Operation Cornet be launched against Honshu on March 1, 1946.

Leahy’s memorandum calling the meeting had asked for casualty projections which that invasion might be expected to produce. Marshall stated that campaigns in the Pacific had been so diverse “it is considered wrong” to make total estimates. All he would say was that casualties during the first thirty days on Kyushu should not exceed those sustained in taking Luzon in the Philippines—31,000 men killed, wounded, or missing in action. “It is a grim fact,” Marshall said, “that there is not an easy, bloodless way to victory in war.” Leahy estimated a higher casualty rate similar to Okinawa, and King guessed somewhere in between.

King and Eaker, speaking for the Navy and the Army Air Forces respectively, endorsed Marshall’s proposals. King said that he had become convinced that Kyushu was “the key to the success of any siege operations.” He recommended that “we should do Kyushu now” and begin preparations for invading Honshu. Eaker “agreed completely” with Marshall. He said he had just received a message from Arnold also expressing “complete agreement.” Air Force plans called for the use of forty groups of heavy bombers, which “could not be deployed without the use of airfields on Kyushu.” Stimson and Forrestal concurred.

Truman summed up. He considered “the Kyushu plan all right from the military standpoint” and directed the chiefs to “go ahead with it.” He said he “had hoped that there was a possibility of preventing an Okinawa from one end of Japan to the other,” but “he was clear on the situation now” and was “quite sure” the chiefs should proceed with the plan. Just before the meeting adjourned, McCloy raised the possibility of avoiding an invasion by warning the Japanese that the United States would employ atomic weapons if there were no surrender. The ensuing discussion was inconclusive because the first test was a month away and no one could be sure the weapons would work.

In his memoirs Truman claimed that using atomic bombs prevented an invasion that would have cost 500,000 American lives. Other officials mentioned the same or even higher figures. Critics have assailed such statements as gross exaggerations designed to forestall scrutiny of Truman’s real motives. They have given wide publicity to a report prepared by the Joint War Plans Committee (JWPC) for the chiefs’ meeting with Truman. The committee estimated that the invasion of Kyushu, followed by that of Honshu, as the chiefs proposed, would cost approximately 40,000 dead, 150,000 wounded, and 3,500 missing in action for a total of 193,500 casualties.

That those responsible for a decision should exaggerate the consequences of alternatives is commonplace. Some who cite the JWPC report profess to see more sinister motives, insisting that such “low” casualty projections call into question the very idea that atomic bombs were used to avoid heavy losses. By discrediting that justification as a cover-up, they seek to bolster their contention that the bombs really were used to permit the employment of “atomic diplomacy” against the Soviet Union.

The notion that 193,500 anticipated casualties were too insignificant to have caused Truman to resort to atomic bombs might seem bizarre to anyone other than an academic, but let it pass. Those who have cited the JWPC report in countless op-ed pieces in newspapers and in magazine articles have created a myth by omitting key considerations: First, the report itself is studded with qualifications that casualties “are not subject to accurate estimate” and that the projection “is admittedly only an educated guess.” Second, the figures never were conveyed to Truman. They were excised at high military echelons, which is why Marshall cited only estimates for the first thirty days on Kyushu. And indeed, subsequent Japanese troop buildups on Kyushu rendered the JWPC estimates totally irrelevent by the time the first atomic bomb was dropped.

Another myth that has attained wide attention is that at least several of Truman’s top military advisers later informed him that using atomic bombs against Japan would be militarily unnecessary or immoral, or both. There is no persuasive evidence that any of them did so. None of the Joint Chiefs ever made such a claim, although one inventive author has tried to make it appear that Leahy did by braiding together several unrelated passages from the admiral’s memoirs. Actually, two days after Hiroshima, Truman told aides that Leahy had “said up to the last that it wouldn’t go off.”

Neither MacArthur nor Nimitz ever communicated to Truman any change of mind about the need for invasion or expressed reservations about using the bombs. When first informed about their imminent use only days before Hiroshima, MacArthur responded with a lecture on the future of atomic warfare and even after Hiroshima strongly recommended that the invasion go forward. Nimitz, from whose jurisdiction the atomic strikes would be launched, was notified in early 1945. “This sounds fine,” he told the courier, “but this is only February. Can’t we get one sooner?” Nimitz later would join Air Force generals Carl D. Spaatz, Nathan Twining, and Curtis LeMay in recommending that a third bomb be dropped on Tokyo.

Only Dwight D. Eisenhower later claimed to have remonstrated against the use of the bomb. In his Crusade in Europe , published in 1948, he wrote that when Secretary Stimson informed him during the Potsdam Conference of plans to use the bomb, he replied that he hoped “we would never have to use such a thing against any enemy,” because he did not want the United States to be the first to use such a weapon. He added, “My views were merely personal and immediate reactions; they were not based on any analysis of the subject.”

Eisenhower’s recollections grew more colorful as the years went on. A later account of his meeting with Stimson had it taking place at Ike’s headquarters in Frankfurt on the very day news arrived of the successful atomic test in New Mexico. “We’d had a nice evening at headquarters in Germany,” he remembered. Then, after dinner, “Stimson got this cable saying that the bomb had been perfected and was ready to be dropped. The cable was in code . . . ‘the lamb is born’ or some damn thing like that.” In this version Eisenhower claimed to have protested vehemently that “the Japanese were ready to surrender and it wasn’t necessary to hit them with that awful thing.” “Well,” Eisenhower concluded, “the old gentleman got furious.”

Myth holds that several of Truman’s top military advisers begged him not to use the bomb. In fact, there is no persuasive evidence that any of them did.

The best that can be said about Eisenhower’s memory is that it had become flawed by the passage of time. Stimson was in Potsdam and Elsenhower in Frankfurt on July 16, when word came of the successful test. Aside from a brief conversation at a flag-raising ceremony in Berlin on July 20, the only other time they met was at Ike’s headquarters on July 27. By then orders already had been sent to the Pacific to use the bombs if Japan had not yet surrendered. Notes made by one of Stimson’s aides indicate that there was a discussion of atomic bombs, but there is no mention of any protest on Eisenhower’s part. Even if there had been, two factors must be kept in mind. Eisenhower had commanded Allied forces in Europe, and his opinion on how close Japan was to surrender would have carried no special weight. More important, Stimson left for home immediately after the meeting and could not have personally conveyed Ike’s sentiments to the President, who did not return to Washington until after Hiroshima.

On July 8 the Combined Intelligence Committee submitted to the American and British Combined Chiefs of Staff a report entitled “Estimate of the Enemy Situation.” The committee predicted that as Japan’s position continued to deteriorate, it might “make a serious effort to use the USSR [then a neutral] as a mediator in ending the war.” Tokyo also would put out “intermittent peace feelers” to “weaken the determination of the United Nations to fight to the bitter end, or to create inter-allied dissension.” While the Japanese people would be willing to make large concessions to end the war, “For a surrender to be acceptable to the Japanese army, it would be necessary for the military leaders to believe that it would not entail discrediting warrior tradition and that it would permit the ultimate resurgence of a military Japan.”

Small wonder that American officials remained unimpressed when Japan proceeded to do exactly what the committee predicted. On July 12 Japanese Foreign Minister Shigenori Togo instructed Ambassador Naotaki Sato in Moscow to inform the Soviets that the emperor wished to send a personal envoy, Prince Fuminaro Konoye, in an attempt “to restore peace with all possible speed.” Although he realized Konoye could not reach Moscow be- fore the Soviet leader Joseph Stalin and Foreign Minister V. M. Molotov left to attend a Big Three meeting scheduled to begin in Potsdam on the fifteenth, Togo sought to have negotiations begin as soon as they returned.

American officials had long since been able to read Japanese diplomatic traffic through a process known as the MAGIC intercepts. Army intelligence (G-2) prepared for General Marshall its interpretation of Togo’s message the next day. The report listed several possible constructions, the most probable being that the Japanese “governing clique” was making a coordinated effort to “stave off defeat” through Soviet intervention and an “appeal to war weariness in the United States.” The report added that Undersecretary of State Joseph C. Grew, who had spent ten years in Japan as ambassador, “agrees with these conclusions.”

Some have claimed that Togo’s overture to the Soviet Union, together with attempts by some minor Japanese officials in Switzerland and other neutral countries to get peace talks started through the Office of Strategic Services (OSS), constituted clear evidence that the Japanese were near surrender. Their sole prerequisite was retention of their sacred emperor, whose unique cultural/religious status within the Japanese polity they would not compromise. If only the United States had extended assurances about the emperor, according to this view, much bloodshed and the atomic bombs would have been unnecessary.

A careful reading of the MAGIC intercepts of subsequent exchanges between Togo and Sato provides no evidence that retention of the emperor was the sole obstacle to peace. What they show instead is that the Japanese Foreign Office was trying to cut a deal through the Soviet Union that would have permitted Japan to retain its political system and its prewar empire intact. Even the most lenient American official could not have countenanced such a settlement.

By late July the casualty projection 31,000 that Marshall had given Truman at the June 18 strategy meeting had become meaningless.

Togo on July 17 informed Sato that “we are not asking the Russians’ mediation in anything like unconditional surrender [emphasis added].” During the following weeks Sato pleaded with his superiors to abandon hope of Soviet intercession and to approach the United States directly to find out what peace terms would be offered. “There is ... no alternative but immediate unconditional surrender,” he cabled on July 31, and he bluntly informed Togo that “your way of looking at things and the actual situation in the Eastern Area may be seen to be absolutely contradictory.” The Foreign Ministry ignored his pleas and continued to seek Soviet help even after Hiroshima.

“Peace feelers” by Japanese officials abroad seemed no more promising from the American point of view. Although several of the consular personnel and military attachés engaged in these activities claimed important connections at home, none produced verification. Had the Japanese government sought only an assurance about the emperor, all it had to do was grant one of these men authority to begin talks through the OSS. Its failure to do so led American officials to assume that those involved were either well-meaning individuals acting alone or that they were being orchestrated by Tokyo. Grew characterized such “peace feelers” as “familiar weapons of psychological warfare” designed to “divide the Allies.”

Some American officials, such as Stimson and Grew, nonetheless wanted to signal the Japanese that they might retain the emperorship in the form of a constitutional monarchy. Such an assurance might remove the last stumbling block to surrender, if not when it was issued, then later. Only an imperial rescript would bring about an orderly surrender, they argued, without which Japanese forces would fight to the last man regardless of what the government in Tokyo did. Besides, the emperor could serve as a stabilizing factor during the transition to peacetime.

There were many arguments against an American initiative. Some opposed retaining such an undemocratic institution on principle and because they feared it might later serve as a rallying point for future militarism. Should that happen, as one assistant Secretary of State put it, “those lives already spent will have been sacrificed in vain, and lives will be lost again in the future.” Japanese hard-liners were certain to exploit an overture as evidence that losses sustained at Okinawa had weakened American resolve and to argue that continued resistance would bring further concessions. Stalin, who earlier had told an American envoy that he favored abolishing the emperorship because the ineffectual Hirohito might be succeeded by “an energetic and vigorous figure who could cause trouble,” was just as certain to interpret it as a treacherous effort to end the war before the Soviets could share in the spoils.

There were domestic considerations as well. Roosevelt had announced the unconditional surrender policy in early 1943, and it since had become a slogan of the war. He also had advocated that peoples everywhere should have the right to choose their own form of government, and Truman had publicly pledged to carry out his predecessor’s legacies. For him to have formally guaranteed continuance of the emperorship, as opposed to merely accepting it on American terms pending free elections, as he later did, would have constituted a blatant repudiation of his own promises.

Nor was that all. Regardless of the emperor’s actual role in Japanese aggression, which is still debated, much wartime propaganda had encouraged Americans to regard Hirohito as no less a war criminal than Adolf Hitler or Benito Mussolini. Although Truman said on several occasions that he had no objection to retaining the emperor, he understandably refused to make the first move. The ultimatum he issued from Potsdam on July 26 did not refer specifically to the emperorship. All it said was that occupation forces would be removed after “a peaceful and responsible” government had been established according to the “freely expressed will of the Japanese people.” When the Japanese rejected the ultimatum rather than at last inquire whether they might retain the emperor, Truman permitted the plans for using the bombs to go forward.

Reliance on MAGIC intercepts and the “peace feelers” to gauge how near Japan was to surrender is misleading in any case. The army, not the Foreign Office, controlled the situation. Intercepts of Japanese military communications, designated ULTRA , provided no reason to believe the army was even considering surrender. Japanese Imperial Headquarters had correctly guessed that the next operation after Okinawa would be Kyushu and was making every effort to bolster its defenses there.

General Marshall reported on July 24 that there were “approximately 500,000 troops in Kyushu” and that more were on the way. ULTRA identified new units arriving almost daily. MacArthur’s G-2 reported on July 29 that “this threatening development, if not checked, may grow to a point where we attack on a ratio of one (1) to one (1) which is not the recipe for victory.” By the time the first atomic bomb fell, ULTRA indicated that there were 560,000 troops in southern Kyushu (the actual figure was closer to 900,000), and projections for November 1 placed the number at 680,000. A report, for medical purposes, of July 31 estimated that total battle and non-battle casualties might run as high as 394,859 for the Kyushu operation alone . This figure did not include those men expected to be killed outright, for obviously they would require no medical attention. Marshall regarded Japanese defenses as so formidable that even after Hiroshima he asked MacArthur to consider alternate landing sites and began contemplating the use of atomic bombs as tactical weapons to support the invasion.

The thirty-day casualty projection of 31,000 Marshall had given Truman at the June 18 strategy meeting had become meaningless. It had been based on the assumption that the Japanese had about 350,000 defenders in Kyushu and that naval and air interdiction would preclude significant reinforcement. But the Japanese buildup since that time meant that the defenders would have nearly twice the number of troops available by “X-day” than earlier assumed. The assertion that apprehensions about casualties are insufficient to explain Truman’s use of the bombs, therefore, cannot be taken seriously. On the contrary, as Winston Churchill wrote after a conversation with him at Potsdam, Truman was tormented by “the terrible responsibilities that rested upon him in regard to the unlimited effusions of American blood.”

Some historians have argued that while the first bomb might have been required to achieve Japanese surrender, dropping the second constituted a needless barbarism. The record shows otherwise. American officials believed more than one bomb would be necessary because they assumed Japanese hard-liners would minimize the first explosion or attempt to explain it away as some sort of natural catastrophe, precisely what they did. The Japanese minister of war, for instance, at first refused even to admit that the Hiroshima bomb was atomic. A few hours after Nagasaki he told the cabinet that “the Americans appeared to have one hundred atomic bombs . . . they could drop three per day. The next target might well be Tokyo.”

Even after both bombs had fallen and Russia entered the war, Japanese militants insisted on such lenient peace terms that moderates knew there was no sense even transmitting them to the United States. Hirohito had to intervene personally on two occasions during the next few days to induce hardliners to abandon their conditions and to accept the American stipulation that the emperor’s authority “shall be subject to the Supreme Commander of the Allied Powers.” That the militarists would have accepted such a settlement before the bombs is farfetched, to say the least.

Some writers have argued that the cumulative effects of battlefield defeats, conventional bombing, and naval blockade already had defeated Japan. Even without extending assurances about the emperor, all the United States had to do was wait. The most frequently cited basis for this contention is the United States Strategic Bombing Survey, published in 1946, which stated that Japan would have surrendered by November 1 “even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.” Recent scholarship by the historian Robert P. Newman and others has demonstrated that the survey was “cooked” by those who prepared it to arrive at such a conclusion. No matter. This or any other document based on information available only after the war ended is irrelevant with regard to what Truman could have known at the time.

What often goes unremarked is that when the bombs were dropped, fighting was still going on in the Philippines, China, and elsewhere. Every day that the war continued thousands of prisoners of war had to live and die in abysmal conditions, and there were rumors that the Japanese intended to slaughter them if the homeland was invaded. Truman was Commander in Chief of the American armed forces, and he had a duty to the men under his command not shared by those sitting in moral judgment decades later. Available evidence points to the conclusion that he acted for the reason he said he did: to end a bloody war that would have become far bloodier had invasion proved necessary. One can only imagine what would have happened if tens of thousands of American boys had died or been wounded on Japanese soil and then it had become known that Truman had chosen not to use weapons that might have ended the war months sooner.

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