Lurking at the back of this story is that same fraught question: what was it that compelled Japan to surrender on 14 August 1945? Was it the atomic bombing of Hiroshima? Of Nagasaki? The combination of the two, which by their rapid occurrence in succession raised Japanese fears that the United States had more atomic bombs on the way and an ongoing willingness to use them? Were the bombs less important than the Soviet decision to declare war on Japan? Or would Japan have surrendered before the end of 1945, as the US Strategic Bombing Survey would have it, even in the absence of the atomic bombs, Soviet intervention, or the prospect of imminent invasion by US military forces? Needless to say, historians and other analysts have divided sharply over the answers to these questions. Understandably so—there is much at stake here. If the atomic bombs, either or both, caused Japan to capitulate, then they arguably saved lives, especially (but not only) American lives, and thus justified the scientific effort and government expense and soothed any moral qualms Americans might have felt about their use. Of course, on the other hand, if the Japanese surrendered for reasons other than the use of the bombs against them, then the Truman administration could stand accused of visiting stark and needless cruelty on a people, on a world, that was lurching toward peace without them. ‘It wasn’t necessary to hit them with that awful thing,’ as Dwight Eisenhower would put it after the war.
Was it? As with all critical historical questions, the answer is complicated. It is rare to find in the record what detectives and historian-detectives call a ‘smoking gun’, a clear expression of cause from a figure in a position to provide one. There is no evidence, for example, that Emperor Hirohito turned to Kido at a crucial moment and said, ‘It is not about those bombs— we cannot have the Russians capturing our soldiers and occupying our land.’ (Even if that statement were discovered in the record, one suspects that historians would question its provenance or subject it to several interpretations.) There is consensus that the views of the Emperor were the key to ending the war, especially as the positions of the members of the Supreme War Council hardly changed between 5 and 14 August. It is true that Yonai’s position was sometimes mysterious, that Suzuki’s wavered briefly after the Byrnes Notes had arrived, and that Anami, while steadfast in opposition to unconditional surrender, significantly refused to support a military coup against his emperor. But it was Hirohito, ghosted by Kido and doubtless influenced by Togo and others, who decided on the 14th that enough was enough. At the first imperial conference on 9-10 August, recall, the Emperor sought to end the war because its continuation could ‘only mean destruction for the nation and prolongation of bloodshed and cruelty to the world’.50 That could mean atomic bombs, a Soviet invasion, or an invasion by the Americans; Hirohito also criticized the military for its lack of preparedness to defend the beaches east of Tokyo. Just before the second imperial conference on the 14th, Hirohito told three senior army officers: ‘The military situation has changed suddenly. The Soviet Union entered the war against us. Suicide attacks can’t compete with the power of science. Therefore, there is no alternative but to accept the Potsdam terms,’ as explicated or confused by the Byrnes Note. Ending the conference itself with his decision to surrender, Hirohito added little to what he had said four days earlier, only that he believed the American proposal would assure the preservation of the kokutai. More revealing was the Emperor’s speech to the nation the following morning. He observed that ‘the enemy has for the first time used cruel bombs to kill and maim extremely large numbers of the innocent, and the heavy casualties are beyond measure. To continue the war further could lead in the end not only to the extermination of our race, but also to the destruction of all human civilization.’ Here was an obvious— not ‘oblique’, as Tsuyoshi Hasegawa has it—reference to the atomic bombs. Ending the war was by Hirohito’s account a ‘magnanimous act’ designed to save not just the Japanese but all humankind from immolation.51
Above all, the Emperor was interested in maintaining his position and in protecting his people from further disaster. His second interest was the servant of his first, for by the summer of 1945 popular disillusionment with Hirohito’s rule was growing, fed by the extraordinary vulnerability of common citizens to American bombs. It was bad enough when incendiary bombs burned Tokyo in March 1945; the sullen reception that greeted Hirohito as he toured the damage spoke volumes about the public’s mood. The police reported on multifarious acts of lese majeste, including someone who said: ‘After having let Tokyo get burned down like that, to hell with His Imperial Highness.’ Intellectuals were more and more disaffected. No one knew how the dazed survivors of Hiroshima and Nagasaki would feel about the Emperor and the government generally, but their reaction was unlikely to be good. Even more ominous was the attitude of the military, which, as events proved, found it enormously difficult to concede defeat. The army and navy seemed willing to fight to the last civilian before capitulating, at least as long as the losses came by attrition. The result of the military’s recklessness could be its own strengthening at the expense of civilian leadership, or rising popular anger over sacrifices demanded without any hope of success. But the shocks administered by the atomic bombs and Soviet entry gave the Emperor good reason to terminate the war; it was harder after 9 August to seek terms. ‘So long as one feels there is any chance left, it is very difficult to say that the chance to quit [has come],’ said Toyoda after the war. In his view, Soviet intervention put an end to hope. Earlier, Yonai had told an aide, ‘the atomic bombs and the Soviet entry into the war are, in a sense, gifts from the gods. This way we don’t have to say that we have quit the war because of domestic circumstances.’ A joke that circulated through Japanese political circles after the war had it that the atomic bomb was ‘the real kamikaze’, delivering the country from further humiliation and death.52
The shocks of August thus gave the Emperor a convenient out, the opening he needed to justify acceptance of the Potsdam Declaration. It may be nothing more than a historian’s common sense to suppose that the infliction of death on many thousands—no one yet knew even roughly how many—by a mere two bombs was, along with Soviet intervention, decisive in ending the war. Given the mix of evidence available, and in the absence of any ‘smoking gun’, common sense may be the best measure possible.