August 9, 1945

August 9, 1945, the day a plutonium bomb devastated Nagasaki, marked a turning point in the emotional and political meaning of the atomic bomb for those who had built it. The attack followed Hiroshima by three days. At Los Alamos, the first exhilaration gave way to revulsion and gloom; beyond the laboratory, the bombing unfolded alongside the Soviet Union’s declaration of war and Japan’s approaching surrender. Nagasaki became both a human catastrophe and a lasting test of the claims made for nuclear weapons and their military purpose.

The bombing and its immediate aftermath

The destruction of Nagasaki followed the Hiroshima bombing of August 6. On the mesa at Los Alamos, the first news from Hiroshima had horrified Robert Wilson, who had continued his work after Robert Oppenheimer persuaded him that the bomb might be demonstrated rather than used against a city. When Nagasaki was devastated three days later, Wilson’s wife, Jane, found him deeply depressed. Other people celebrated noisily, but Wilson refused to join them; he recalled feeling so sick that he thought he might vomit.

Wilson’s distress was part of a broader change in the laboratory’s mood. Many at Los Alamos had felt a moment of exhilaration after Hiroshima, but after Nagasaki, Charlotte Serber observed a palpable gloom settling over the community. An FBI informant reported Oppenheimer as a nervous wreck on August 9. Word circulated that he believed the atomic bomb was so terrible a weapon that war had become impossible. The prospect of victory did not settle the question of what the weapon had done, or what its existence would mean afterward.

The sequence of military and diplomatic events intensified that uncertainty. On August 8, the Soviet Union declared war on Japan, as it had promised at Yalta and confirmed at Potsdam. Two days after Nagasaki, the Japanese government offered to surrender on the condition that the emperor’s status be guaranteed. The Allies clarified that the emperor’s authority would remain subject to the Allied Supreme Commander; on August 14, Radio Tokyo announced Japan’s acceptance. The war was over, but journalists and historians soon debated whether it might have ended around the same time on similar terms without the atomic bomb.

Witnessing the human cost

The consequences became more immediate for people at Los Alamos when scientific observers returned from Japan in October. Phil Morrison described the effects of the Hiroshima blast to the community, including people burned over a wide area and survivors who later died from radiation injuries. His account made the destruction difficult to hold at the distance encouraged by technical work: Jean Bacher recalled that hearing him left her unable to sleep, shaking from the shock.

Bob Serber brought back an image from Nagasaki that Oppenheimer treated as a rebuke to casual descriptions of the weapon. Serber had followed telephone poles charred on the sides facing the explosion, tracing the marks beyond two miles from ground zero. He also saw a horse whose hair had been burned away on one side while the other remained normal. When Serber remarked that it seemed to be grazing happily, Oppenheimer scolded him for giving the impression that the bomb was benevolent. The animal’s unevenly burned body made the blast’s reach visible; Oppenheimer’s response insisted that survival amid devastation could not be mistaken for harmlessness.

From wartime weapon to strategic dilemma

Nagasaki also entered later arguments over what kind of nuclear arsenal could plausibly serve military and political purposes. In 1949, as the United States considered a far more powerful thermonuclear weapon, Oppenheimer and the majority of the General Advisory Committee argued that such a weapon would be too destructive to confine to legitimate military targets. The Hiroshima bomb had a yield of 15,000 tons of TNT; a feasible thermonuclear bomb, they warned, might reach 100 million tons and destroy hundreds of square miles. The committee feared that it could become a weapon of genocide and that possessing it would damage American security as well as world opinion.

The committee’s alternative was not simply to accumulate ever larger weapons. It argued that a refusal to build the Super might reopen arms-control negotiations, while increased production of fissionable material for smaller tactical atomic weapons could offer a more credible deterrent. Oppenheimer supported that proposal, but the preference carried its own danger. In the 1951 Project Vista report, he described tactical weapons as aids to battlefield forces rather than instruments of totality or terror. The shift away from city-destroying strategy could bring nuclear weapons closer to actual combat, creating the possibility of escalation that his argument did not resolve.

The event’s continuing significance

Nagasaki was followed by surrender, but the sequence did not itself answer whether the bombing had been necessary. The surrender offer came after the Soviet declaration of war and after the destruction of the second city; the postwar debate therefore turned on the interaction of military action, diplomacy, and the terms Japan ultimately accepted. For the scientists who had made the bomb, the return accounts from Hiroshima and Nagasaki further collapsed the distance between a weapon’s design and its consequences for civilians.

The event also shadowed Oppenheimer’s later effort to assess nuclear policy in moral as well as technical terms. His opposition to the Super rested in part on the conviction that a weapon capable of annihilating vast areas could not be treated as an ordinary instrument of military planning. Yet his support for tactical nuclear weapons showed the unresolved tension in his search for an alternative: an arsenal conceived as more limited might appear more usable. Nagasaki thus remained not only a second catastrophe in the closing days of the war, but a concrete measure against which subsequent claims of nuclear restraint had to be judged.