The atomic bombing of Hiroshima, Japan, on 6 August 1945, seems in many ways an event characterized by clarity and even simplicity. From a clear blue sky on a radiantly hot summer morning came a single American B-29 bomber (warily flanked by two observation planes), carrying a single bomb. The plane was called the Enola Gay, after its pilot’s mother; the bomb bore the innocent nickname ‘Little Boy’. There were no Japanese fighter planes to challenge the Enola Gay, no airbursts of flak in its way. Japanese civil defense, evidently having been fooled by a lone American reconnaissance plane over the city an hour before, now did not bother to sound the alert that would have sent people in Hiroshima to air-raid shelters. The target of the bomb was the Aioi Bridge, which spanned the Ota River at the heart of the city. At 8.15 Hiroshima time the crew of the Enola Gay released the bomb. Forty-three seconds later, at an altitude of about 1,900 feet, Little Boy exploded.
One plane, one city, one morning in August, one atomic bomb: simple. The commander of the Enola Gay, a 29-year-old air-force colonel named Paul W Tibbets, had practiced many times during the preceding weeks and months dropping mock equivalents of atomic bombs, filled with concrete and high explosives, on an isolated patch of the Utah desert and in the Pacific Ocean. The way his plane bounced upwards once the bomb had been dropped and then detonated was no surprise to him. That the bomb worked, creating an awesome cloud of fire and smoke and dirt and buffeting the Enola Gay with its shock wave, was testimony to the technological competence of an American-based team of scientists, who had solved many (though hardly all) of the scientific problems the Second World War had presented. And there seemed to the crew of the plane that bright morning a moral simplicity to what they had done. The criminality of the Japanese—all Japanese, without distinction—was to them unquestionable.
The Japanese had treacherously attacked Pearl Harbor. They had murdered civilians in China and Southeast Asia, tortured and starved their prisoners, and fought remorselessly for their island conquests in the South Pacific. If dropping an atomic bomb above the center of Hiroshima would end the war sooner, the men of the Enola Gay would simply do it, without hesitation and untroubled by pangs of conscience.
Over sixty years after the atomic bombing of Hiroshima (and Nagasaki, bombed three days later), we remember the event with much of the same stark simplicity with which it was regarded at the time. The atomic bomb, many claim, was an appropriate punishment for a people who had visited war and misery on the world, a punishment commensurate with Japanese malfeasance in Asia and throughout the Pacific. The Japanese deserved the bomb. Moreover, the bomb was essential to end the war. The Japanese war cabinet, or influential members of it, had vowed to sacrifice multitudes of their fellow citizens in defending their homeland against an anticipated invasion by the United States. The devastating firebombings of Japanese cities, including Tokyo, had not caused military officials to waver. Only a shock as powerful as the one the atomic bombs administered was sufficient to convince Japan’s leaders, including the Emperor Hirohito, to quit the war on reasonable terms. The bombs thus saved hundreds of thousands of Japanese and American lives.
Or: The atomic bomb was a weapon so heinous in its composition, so willfully indiscriminate, so simply and obviously aimed at ordinary people, that its use was a moral outrage, even if it might in the end have saved lives. No people, regardless of the behavior of their government, deserves annihilation by a weapon as terrible as a nuclear bomb. In its very singularity as an instrument of war the atomic bomb stood condemned. It was the only known weapon to destroy so much by itself, to create such a powerful blast, such a devastating fire, and—perhaps above all— to spread radioactivity throughout its targeted place, with consequences as fearsome as they were at the time poorly understood. And, critics charged, the atomic bombings of Hiroshima and Nagasaki were unnecessary to win the war. Japan was near defeat by the summer of 1945, and some cabinet members, and possibly even the Emperor himself, were frantically looking for a way to surrender to the Americans while saving a measure of face and preserving the imperial system of rule. Had the Americans modified even slightly the terms of surrender, guaranteeing that Hirohito would keep his life and his position, Tokyo would have conceded. The Americans knew this. They used the bombs anyway in order to see what their new weapon— a $2 billion investment—would do to a city, and especially to end the Pacific War before the Soviet Union could enter it fully, and thereby demand a prominent role in the reconstruction of postwar Japan. The use of the bombs would in addition intimidate potential adversaries, serving notice, particularly in Moscow, that the United States had harnessed the power of the nucleus and would not scruple to use it.
But, of course, the atomic bombing of Hiroshima was not so simple, neither in 1945 nor today. That the dispute about its use remains bitter is evidence of that. The questions linger. Were the Japanese on their last legs by the summer of 1945? Did their leaders know it? Did the Americans think the Japanese leaders knew it? Was the bomb necessary to end the war? Were both bombs needed? In their absence, or with a decision not to use them, would it have taken a bloody American invasion of Japan itself to achieve surrender? Or would the war have ended, as the US Strategic Bombing Survey concluded in July 1946, ‘certainly’ before the end of 1945 ‘and in all probability prior to 1 November 1945 ... 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’?1 Would it have been enough for the United States to have modified its demand that Japan surrender unconditionally, perhaps by signaling that the imperial system, the kokutai, could be retained? Was the bomb used chiefly not for military reasons but to intimidate the Soviet Union?
And yet, even these difficult and complex questions, along with their fraught and complicated and necessarily qualified answers, frame the argument too simply. For the atomic bombing of Hiroshima was not merely a decision made by US policymakers in order to punish the Japanese, not just an issue in Japan-US relations, but instead the product of years of scientific experimentation, ethical debate within the scientific community, and significant changes in the conduct of war—all undertaken globally. Americans alone did not decide to build the bomb, and neither did they alone actually build it. The science that enabled the bomb was conducted internationally; Hungarian, British, and German scientists and mathematicians, for example, were among the bomb’s most important theoretical pioneers. Even after many of the world’s leading mathematicians, physicists, and chemists had gathered in the United States and had combined their talents in the top-secret Manhattan Project, other scientists remained in their home countries, contributing to fledgling atomic bomb programs.
Limited by doubting governments and scarce resources, these programs nevertheless sustained the international scope of the pursuit of nuclear power, and internationalized as well the scientific and ethical debates over the atomic bomb that emerged with new intensity after August 1945.
If the making of the atomic bomb and the discussion that surrounded it had international sources, so too did the bomb have implications that stretched beyond the territories of the United States and Japan and well beyond the sensibilities of Americans and Japanese. News of the Hiroshima bombing was greeted with profound shock everywhere. A Mexican newspaper likened it to an earthquake, while a Trinidadian paper chose a comparison to a volcano—both familiar yet potentially catastrophic occurrences that were beyond human responsibility or control. The bomb killed mostly Japanese, of course, but also many Koreans and Chinese, and (indirectly) a few Americans, none of whom was in Hiroshima that dreadful morning by choice. Otto Hahn, one of the Germans who had discovered fission in 1938, was badly shaken by news of Hiroshima and blamed himself for the hundreds of thousands of deaths, while Werner Heisenberg, head of the German atomic-bomb project throughout much of the war, would not believe that the news was true.2 When the Soviet dictator Josef Stalin heard about Hiroshima, he called in his scientists and declared himself fully for a crash program to build a Soviet atomic bomb. The British, proud of their contribution to the Manhattan Project—there were nineteen British scientists at the laboratory at Los Alamos, New Mexico, where the bomb was designed—decided nonetheless to build their own bombs. So, ultimately, did the governments of France, Israel, China, South Africa, India, Pakistan, North Korea, and possibly Iran.
The atomic-bomb tests that followed the Hiroshima and Nagasaki bombings put into the air radiation that no human-made boundary could contain. The waste products of nuclear reactors, on line for peaceful or warlike purposes, threatened to poison ground water as well. Fear of a nuclear nightmare also transcended nations. The creation of Soviet or (mostly) US military bases that held, or were reputed to hold, nuclear weapons within their gates—bases in the Philippines, Okinawa, Cuba, Turkey, and England—brought home to nearby residents the possibility that they might be the targets of a nuclear attack or victims of a nuclear accident. Resistance to the testing and deployment of nuclear weapons ranged far and wide, from Japan and Oceania to Europe and the United States. Popular culture, including literature, art, music, and even humor, reflected global fears of nuclear war, and just as often a heady defiance of those apparently willing to wage or countenance it.
The uranium-based bomb that was dropped on Hiroshima was thus the world’s bomb. While it was an American’s hand that released the bomb from the belly of the Enola Gay, and while Japanese died in droves that morning as a result, the atomic bomb was in a meaningful sense everyone’s offspring and certainly thereafter everyone’s problem. Had the Japanese, or the Germans, the British, or the Soviets made the bomb first, they surely would have used it against their enemies; that they did not get the bomb first had nothing to do with any moral qualms about producing it. No one’s hands were entirely clean. Otto Frisch, the Austrian who came to Los Alamos and worked on assembling the critical mass essential for a nuclear chain reaction, felt nauseated when his fellow scientists celebrated the destruction of Hiroshima, while the Hungarian scientist Leo Szilard told a correspondent that the bombing was ‘one of the greatest blunders in history’, eroding as it did ‘our own moral position’. Robert Oppenheimer, scientific head of the Manhattan Project, lamented to President Harry S. Truman that he had ‘blood on his hands’ because of his contribution to the bomb. (According to some accounts, Truman caustically offered Oppenheimer a handkerchief to wipe the blood off.) ‘As far as I can see,’ said Mahatma Gandhi, ‘the atomic bomb has deadened the finest feelings which have sustained mankind for ages’—meaning that everyone, not just the immediate perpetrators of the bomb, had been morally compromised.3
This book tells the story of the Hiroshima bomb. It will explore, in layperson’s terms, the physics of the bomb, the international crises that led to the Second World War, the creation of a community of scientists, throughout the world and especially in the United States during the 1930s and 1940s, dedicated to developing a weapon that could undo the evil that resided in Nazi Germany, the harnessing of their efforts by the wartime state, the political and strategic decisions that led to the bombing itself, the impact of the bomb on Hiroshima and the endgame of the Pacific War, the largely unavailing attempts to control the spread of nuclear weapons in the war’s aftermath and the evolution of the nuclear arms race, the effects of the bombing and the bomb on society and culture, and the state of things nuclear in the early twenty-first-century world. Throughout, the account will contextualize the event—too seldom regarded as the place—we call Hiroshima as an episode in international history, not solely the consequence of wartime hatreds that marked the American-Japanese relationship in 1941-5. The result, I hope, is a serious, readable overview of one of the truly critical moments in the history of the twentieth-century world and all human history. ‘The scientists, helped by the engineers, had drawn a line across history so that the centuries before August 6, 1945, were sharply separated from the years to come,’ wrote the historian Margaret Gowing. ‘And though perhaps they did not contemplate the technical “escalation” of the next fifteen years nor think in terms of megatons and megadeaths, of weapons that could obliterate not a single town but half a country, they knew that the atomic age had only begun.’4 More than sixty years later, the Cold War is past, the danger of a nation-to-nation exchange of nuclear bombs or warheads seemingly diminished. Yet in an age of stateless terrorism and great power arrogance, where international norms and institutions appear helpless to prevent violence and nuclear materials go ominously missing, where there are no longer one or two nuclear nations but perhaps ten, we may wonder whether the world is safer from nuclear holocaust than it was in the bewildering days following that clear August morning in 1945.