There was, as Robert Wilson suggested, an assumption in the air that, if a bomb became feasible while the enemy—any enemy—was still in the field, it should be used; it would have been, as Wilson put it, ‘unrealistic and unfair’ to have asked the scientists to stop their work and the United States to stop its fight. Roosevelt seems to have assumed this, and when, in late 1943, Leslie Groves began retrofitting a B-29, largely designated for use in the Pacific theater, to carry the bomb, it was clear that he, too, planned to use his weapon against any and all enemies. Roosevelt’s and Groves’s decisions were the ones that mattered most, and most of the scientists working on the bomb, like Robert Wilson, accepted this. But even before Germany had surrendered, several of those involved with the Manhattan Project, convinced that the great evil of Nazism had been subdued and the danger of a German atomic bomb had passed, argued that the bomb ought not to be used against Japan. In other words, the target of the bomb should be understood as having been defeated, and the bomb’s aiming point not merely shifted to another nation. It must be said that there was not much sympathy for the Japanese themselves—while the Jewish refugee scientists especially regarded them as less malignant than the Nazis, most also remembered Pearl Harbor, read the news of the ferocious island-hopping campaign, and shared the view, held by most white Americans, that the Japanese were not quite human. Instead, the scientists’ major concern was that combat use of the bomb against Japan would set a bad precedent for the rest of the world and would in particular antagonize the Soviet Union, which would feel threatened by the US attack and would consider it necessary to race ahead with a bomb-building project of its own.27
Niels Bohr was an early advocate of informing the Soviet Union about the bomb project, thereby hastening a return to the republic of science and an ‘open world’ of information exchange. Bohr had traveled to Los Alamos in 1944 and had there advocated, in his elliptical way of speaking, the use of the bomb as a symbol of international hope and an opportunity for international cooperation. He did not, apparently, recommend specifically against using the bomb in Japan, but he stressed the singular evil of Hitler and told Oppenheimer confidently that ‘nothing like’ Nazism ‘would ever happen again’. Leo Szilard went further. Szilard had energetically promoted the bomb, and to him belongs a good deal of credit for harassing US authorities into taking the project seriously early in the European war. Gradually, however, Szilard’s gifts as a scientist became less relevant to the task of crafting the bomb itself. In early 1945, as Germany’s defeat loomed, Szilard decided to talk to Roosevelt about the urgent need for postwar control of nuclear weapons. He solicited a letter of introduction from Albert Einstein, gained permission to take his cause to the President from Arthur Compton, and secured, through Eleanor Roosevelt, an appointment at the White House—for 8 May 1945. When FDR died on 12 April, Szilard managed to reschedule with Truman. He got as far as the office of Truman’s appointment secretary Matthew Connelly, who assured Szilard that his boss took him seriously, then shunted him off to South Carolina for a meeting with James Byrnes, the man who was soon to be secretary of state, though Szilard did not know this.28
Szilard took Harold Urey and University of Chicago dean Walter Bartky along for support; the men arrived by train in Spartanburg on 28 May. Szilard presented Byrnes with Einstein’s letter and read a memo, which suggested that dropping a bomb on Japan would probably move the Soviets more quickly toward making a bomb of their own. Byrnes remonstrated. Groves, he said, had told him that there was no uranium in the Soviet Union. Having spent $2 billion on the bomb, not to use it against Japan would ultimately dismay Congress and make it difficult to get funding for nuclear research in the future. And, Byrnes implied, the Soviets, who seemed to him up to no good in the East European nations they had liberated from Germany, might be easier to deal with if the United States dropped an atomic bomb. At this point, Szilard remembered, ‘I began to doubt that there was any way for me to communicate with Byrnes in this matter.’ Szilard and his colleagues took their leave in a fog of depression.29
Szilard returned to the Met Lab and discovered he had, as he often had, generated controversy. The Army was angry that Szilard had been permitted to get to Connelly and especially Byrnes. Bartky was reprimanded by Groves and scolded for giving Szilard’s memo to Byrnes; Groves considered Szilard ‘an opportunist’ with ‘no moral standards of any kind’. Compton loyally backed his scientists, and, as the high-level Interim Committee began its deliberations, he deputed James Franck, the head of Met Lab’s chemistry section, to write a report examining the probable consequences of the bomb’s use. Franck had serious reservations about using the bomb, and had in fact exacted a promise from Compton, in 1942, that, if an American bomb was ready before Germany or another nation had one, Franck could object to its use at the highest level of government. Franck, who was fondly called ‘Pa’ by his co-workers and had a reputation for rectitude, rushed to his conclusions, and sent his thirteen-page report to Secretary of War Stimson on 11 June—though, as things turned out, it did not reach Stimson’s desk.30
Franck knew the reasons why many were promoting the use of the bomb, or he anticipated them with remarkable acuity. Some said that using bombs would end the war quickly and thus save American lives. Franck doubted that the first generation of nuclear weapons would be powerful enough to discourage the Japanese from continuing the fight. Moreover, even if the bombs did shorten the war and thus keep American soldiers alive, that benefit ‘may be outweighed by the ensuing loss of confidence and wave of horror and repulsion’ the world would feel if the bombs were dropped. The huge expense for the Manhattan Project, mentioned to Szilard by Byrnes, did not require the bombs’ use; the American public would understand ‘that a weapon can sometimes be made ready only for use in an extreme emergency’, and that nuclear weapons were in this category. The ‘compelling reason’ to build the weapon had been the scientists’ fear that Germany might be building one too, but that was no longer an issue. Above all, using the bomb against a Japanese city would so shock the world as to make future control of nuclear weapons unlikely. The bomb was ‘something entirely new in the order of magnitude of destructive power’. Given that, the way forward was to arrange a demonstration of the weapon in ‘the desert or [on] a barren island’, to which representatives from all nations, including of course Japan and the Soviet Union, would be invited. If the Japanese saw the awful power of the bomb, they might surrender. If the Russians and others saw that the Americans had the bomb but were too merciful to use it, they might be persuaded to place nuclear weapons work under international control.31
Military and government officials either remained unaware of the Franck Report or ignored it. Still, dissent continued. A gas diffusion engineer named O. C. Brewster got a letter through to Stimson on 24 May in which he insisted that, if the United States dropped the bomb, ‘we would be the most hated and feared nation on earth’. George Harrison, Stimson’s special assistant, wrote to his boss on 26 June of scientists’ concerns about the bombs’ use leading to a nuclear arms race. In July, Szilard tried again, circulating at the Met Lab a petition calling on the government to refrain, ‘on moral grounds’, from using the bomb against Japanese cities. He got fifty-three signatures at first, then toned down his language slightly and gained seventeen more. But he could not win over the Lab’s chemists, nor could he persuade Oppenheimer or Edward Teller, both at Los Alamos, to sign. (Oppie refused even to circulate the document.) The petition went through channels to Groves, who sat on it until 1 August, when he sent it to Stimson. President Truman, who had been in Potsdam and was then returning home aboard ship, never saw it.32
There were also several high-ranking doubters, men involved in atomic-bomb decisionmaking, who shared, perhaps independently, the scientists’ concerns about dropping the bomb on Japanese cities, or who had different concerns that nevertheless brought them to some of the same, troubled conclusions. With Barton J. Bernstein, we can probably dismiss the postwar statement of wartime opposition to using the bomb made by Dwight Eisenhower. Bernstein casts similar doubt on post facto remarks criticizing the attacks by three of the four members of the 1945 Joint Chiefs of Staff: Admiral Ernest King, Army Air Force General Henry Arnold, and Admiral William Leahy, the chairman of the chiefs whose 1950 memoir, incongruously endorsed by Truman, described the use of the bomb as barbaric. The fourth member of the JCS, George Marshall, did privately urge Stimson, on 29 June, to confine use of the bomb to a genuinely military target. When the administration instead agreed to target Hiroshima and other cities, Marshall kept his counsel. Joseph Grew, the Undersecretary of State and former Ambassador to Japan, urged Truman in late May to signal the Japanese that even in surrender they could retain control of their political system, meaning that the office and the person of the Emperor would be preserved. Grew’s proposal came in the aftermath of the latest firebombing attack on Tokyo; the atomic bomb lurked only in shadow form behind his argument to the President. Truman sent Grew off to see Stimson and several military leaders, who objected that such a concession would signal weakness to the Japanese even as the battle continued for Okinawa. Most forceful among the dissenters was Ralph Bard, undersecretary of the navy and a member of the Interim Committee. Bard was convinced, as he wrote to George Harrison on 27 June, that the Japanese were looking for a way to capitulate. If perhaps Japan was warned about the bomb, even a few days before it was to be used, and if perhaps the President could make ‘assurances’ to Tokyo regarding the Emperor, the Japanese would surrender unconditionally. Bard saw nothing to lose by trying.33