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Why Truman Dropped the Bomb

From the August 8, 2005 issue: Sixty years after Hiroshima, we now have the secret intercepts that shaped his decision.

Aug 8, 2005, Vol. 10, No. 44 • By RICHARD B. FRANK
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An inner cabinet in Tokyo authorized Japan's only officially sanctioned diplomatic initiative. The Japanese dubbed this inner cabinet the Big Six because it comprised just six men: Prime Minister Kantaro Suzuki, Foreign Minister Shigenori Togo, Army Minister Korechika Anami, Navy Minister Mitsumasa Yonai, and the chiefs of staff of the Imperial Army (General Yoshijiro Umezu) and Imperial Navy (Admiral Soemu Toyoda). In complete secrecy, the Big Six agreed on an approach to the Soviet Union in June 1945. This was not to ask the Soviets to deliver a "We surrender" note; rather, it aimed to enlist the Soviets as mediators to negotiate an end to the war satisfactory to the Big Six--in other words, a peace on terms satisfactory to the dominant militarists. Their minimal goal was not confined to guaranteed retention of the Imperial Institution; they also insisted on preservation of the old militaristic order in Japan, the one in which they ruled.

The conduit for this initiative was Japan's ambassador in Moscow, Naotake Sato. He communicated with Foreign Minister Togo--and, thanks to code breaking, with American policymakers. Ambassador Sato emerges in the intercepts as a devastating cross-examiner ruthlessly unmasking for history the feebleness of the whole enterprise. Sato immediately told Togo that the Soviets would never bestir themselves on behalf of Japan. The foreign minister could only insist that Sato follow his instructions. Sato demanded to know whether the government and the military supported the overture and what its legal basis was--after all, the official Japanese position, adopted in an Imperial Conference in June 1945 with the emperor's sanction, was a fight to the finish. The ambassador also demanded that Japan state concrete terms to end the war, otherwise the effort could not be taken seriously. Togo responded evasively that the "directing powers" and the government had authorized the effort--he did not and could not claim that the military in general supported it or that the fight-to-the-end policy had been replaced. Indeed, Togo added: "Please bear particularly in mind, however, that we are not seeking the Russians' mediation for anything like an unconditional surrender."

This last comment triggered a fateful exchange. Critics have pointed out correctly that both Under Secretary of State Joseph Grew (the former U.S. ambassador to Japan and the leading expert on that nation within the government) and Secretary of War Henry Stimson advised Truman that a guarantee that the Imperial Institution would not be eliminated could prove essential to obtaining Japan's surrender. The critics further have argued that if only the United States had made such a guarantee, Japan would have surrendered. But when Foreign Minister Togo informed Ambassador Sato that Japan was not looking for anything like unconditional surrender, Sato promptly wired back a cable that the editors of the "Magic" Diplomatic Summary made clear to American policymakers "advocate[s] unconditional surrender provided the Imperial House is preserved." Togo's reply, quoted in the "Magic" Diplomatic Summary of July 22, 1945, was adamant: American policymakers could read for themselves Togo's rejection of Sato's proposal--with not even a hint that a guarantee of the Imperial House would be a step in the right direction. Any rational person following this exchange would conclude that modifying the demand for unconditional surrender to include a promise to preserve the Imperial House would not secure Japan's surrender.

Togo's initial messages--indicating that the emperor himself endorsed the effort to secure Soviet mediation and was prepared to send his own special envoy--elicited immediate attention from the editors of the "Magic" Diplomatic Summary, as well as Under Secretary of State Grew. Because of Grew's documented advice to Truman on the importance of the Imperial Institution, critics feature him in the role of the sage counsel. What the intercept evidence discloses is that Grew reviewed the Japanese effort and concurred with the U.S. Army's chief of intelligence, Major General Clayton Bissell, that the effort most likely represented a ploy to play on American war weariness. They deemed the possibility that it manifested a serious effort by the emperor to end the war "remote." Lest there be any doubt about Grew's mindset, as late as August 7, the day after Hiroshima, Grew drafted a memorandum with an oblique reference to radio intelligence again affirming his view that Tokyo still was not close to peace.

Starting with the publication of excerpts from the diaries of James Forrestal in 1951, the contents of a few of the diplomatic intercepts were revealed, and for decades the critics focused on these. But the release of the complete (unredacted) "Magic" Far East Summary, supplementing the Diplomatic Summary, in the 1990s revealed that the diplomatic messages amounted to a mere trickle by comparison with the torrent of military intercepts. The intercepts of Japanese Imperial Army and Navy messages disclosed without exception that Japan's armed forces were determined to fight a final Armageddon battle in the homeland against an Allied invasion. The Japanese called this strategy Ketsu Go (Operation Decisive). It was founded on the premise that American morale was brittle and could be shattered by heavy losses in the initial invasion. American politicians would then gladly negotiate an end to the war far more generous than unconditional surrender.
Ultra was even more alarming in what it revealed about Japanese knowledge of American military plans. Intercepts demonstrated that the Japanese had correctly anticipated precisely where U.S. forces intended to land on Southern Kyushu in November 1945 (Operation Olympic). American planning for the Kyushu assault reflected adherence to the military rule of thumb that the attacker should outnumber the defender at least three to one to assure success at a reasonable cost. American estimates projected that on the date of the landings, the Japanese would have only three of their six field divisions on all of Kyushu in the southern target area where nine American divisions would push ashore. The estimates allowed that the Japanese would possess just 2,500 to 3,000 planes total throughout Japan to face Olympic. American aerial strength would be over four times greater.

From mid-July onwards, Ultra intercepts exposed a huge military buildup on Kyushu. Japanese ground forces exceeded prior estimates by a factor of four. Instead of 3 Japanese field divisions deployed in southern Kyushu to meet the 9 U.S. divisions, there were 10 Imperial Army divisions plus additional brigades. Japanese air forces exceeded prior estimates by a factor of two to four. Instead of 2,500 to 3,000 Japanese aircraft, estimates varied between about 6,000 and 10,000. One intelligence officer commented that the Japanese defenses threatened "to grow to [the] point where we attack on a ratio of one (1) to one (1) which is not the recipe for victory."

Concurrent with the publication of the radio intelligence material, additional papers of the Joint Chiefs of Staff have been released in the last decade. From these, it is clear that there was no true consensus among the Joint Chiefs of Staff about an invasion of Japan. The Army, led by General George C. Marshall, believed that the critical factor in achieving American war aims was time. Thus, Marshall and the Army advocated an invasion of the Home Islands as the fastest way to end the war. But the long-held Navy view was that the critical factor in achieving American war aims was casualties. The Navy was convinced that an invasion would be far too costly to sustain the support of the American people, and hence believed that blockade and bombardment were the sound course.

The picture becomes even more complex than previously understood because it emerged that the Navy chose to postpone a final showdown over these two strategies. The commander in chief of the U.S. fleet, Admiral Ernest King, informed his colleagues on the Joint Chiefs of Staff in April 1945 that he did not agree that Japan should be invaded. He concurred only that the Joint Chiefs must issue an invasion order immediately to create that option for the fall. But King predicted that the Joint Chiefs would revisit the issue of whether an invasion was wise in August or September. Meanwhile, two months of horrendous fighting ashore on Okinawa under skies filled with kamikazes convinced the commander in chief of the Pacific Fleet, Admiral Chester Nimitz, that he should withdraw his prior support for at least the invasion of Kyushu. Nimitz informed King of this change in his views in strict confidence.

In August, the Ultra revelations propelled the Army and Navy towards a showdown over the invasion. On August 7 (the day after Hiroshima, which no one expected to prompt a quick surrender), General Marshall reacted to weeks of gathering gloom in the Ultra evidence by asking General Douglas MacArthur, who was to command what promised to be the greatest invasion in history, whether invading Kyushu in November as planned still looked sensible. MacArthur replied, amazingly, that he did not believe the radio intelligence! He vehemently urged the invasion should go forward as planned. (This, incidentally, demolishes later claims that MacArthur thought the Japanese were about to surrender at the time of Hiroshima.)
On August 9 (the day the second bomb was dropped, on Nagasaki), King gathered the two messages in the exchange between Marshall and MacArthur and sent them to Nimitz. King told Nimitz to provide his views on the viability of invading Kyushu, with a copy to MacArthur. Clearly, nothing that had transpired since May would have altered Nimitz's view that Olympic was unwise. Ultra now made the invasion appear foolhardy to everyone but MacArthur. But King had not placed a deadline on Nimitz's response, and the Japanese surrender on August 15 allowed Nimitz to avoid starting what was certain to be one of the most tumultuous interservice battles of the whole war.

What this evidence illuminates is that one central tenet of the traditionalist view is wrong--but with a twist. Even with the full ration of caution that any historian should apply anytime he ventures comments on paths history did not take, in this instance it is now clear that the long-held belief that Operation Olympic loomed as a certainty is mistaken. Truman's reluctant endorsement of the Olympic invasion at a meeting in June 1945 was based in key part on the fact that the Joint Chiefs had presented it as their unanimous recommendation. (King went along with Marshall at the meeting, presumably because he deemed it premature to wage a showdown fight. He did comment to Truman that, of course, any invasion authorized then could be canceled later.) With the Navy's withdrawal of support, the terrible casualties in Okinawa, and the appalling radio-intelligence picture of the Japanese buildup on Kyushu, Olympic was not going forward as planned and authorized--period. But this evidence also shows that the demise of Olympic came not because it was deemed unnecessary, but because it had become unthinkable. It is hard to imagine anyone who could have been president at the time (a spectrum that includes FDR, Henry Wallace, William O. Douglas, Harry Truman, and Thomas Dewey) failing to authorize use of the atomic bombs in this circumstance.
Japanese historians uncovered another key element of the story. After Hiroshima (August 6), Soviet entry into the war against Japan (August 8), and Nagasaki (August 9), the emperor intervened to break a deadlock within the government and decide that Japan must surrender in the early hours of August 10. The Japanese Foreign Ministry dispatched a message to the United States that day stating that Japan would accept the Potsdam Declaration, "with the understanding that the said declaration does not comprise any demand which prejudices the prerogatives of His Majesty as a Sovereign Ruler." This was not, as critics later asserted, merely a humble request that the emperor retain a modest figurehead role. As Japanese historians writing decades after the war emphasized, the demand that there be no compromise of the "prerogatives of His Majesty as a Sovereign Ruler" as a precondition for the surrender was a demand that the United States grant the emperor veto power over occupation reforms and continue the rule of the old order in Japan. Fortunately, Japan specialists in the State Department immediately realized the actual purpose of this language and briefed Secretary of State James Byrnes, who insisted properly that this maneuver must be defeated. The maneuver further underscores the fact that right to the very end, the Japanese pursued twin goals: not only the preservation of the imperial system, but also preservation of the old order in Japan that had launched a war of aggression that killed 17 million.

This brings us to another aspect of history that now very belatedly has entered the controversy. Several American historians led by Robert Newman have insisted vigorously that any assessment of the end of the Pacific war must include the horrifying consequences of each continued day of the war for the Asian populations trapped within Japan's conquests. Newman calculates that between a quarter million and 400,000 Asians, overwhelmingly noncombatants, were dying each month the war continued. Newman et al. challenge whether an assessment of Truman's decision can highlight only the deaths of noncombatant civilians in the aggressor nation while ignoring much larger death tolls among noncombatant civilians in the victim nations.

There are a good many more points that now extend our understanding beyond the debates of 1995. But it is clear that all three of the critics' central premises are wrong. The Japanese did not see their situation as catastrophically hopeless. They were not seeking to surrender, but pursuing a negotiated end to the war that preserved the old order in Japan, not just a figurehead emperor. Finally, thanks to radio intelligence, American leaders, far from knowing that peace was at hand, understood--as one analytical piece in the "Magic" Far East Summary stated in July 1945, after a review of both the military and diplomatic intercepts--that "until the Japanese leaders realize that an invasion can not be repelled, there is little likelihood that they will accept any peace terms satisfactory to the Allies." This cannot be improved upon as a succinct and accurate summary of the military and diplomatic realities of the summer of 1945.

The displacement of the so-called traditionalist view within important segments of American opinion took several decades to accomplish. It will take a similar span of time to displace the critical orthodoxy that arose in the 1960s and prevailed roughly through the 1980s, and replace it with a richer appreciation for the realities of 1945. But the clock is ticking.

Richard B. Frank, a historian of World War II, is the author of Downfall: The End of the Imperial Japanese Empire.