After Germany’s surrender on May 7, 1945, the war continued in the Pacific, as did planning for the invasion of Japan. Allied military leaders believed invasion was the only way to force the unconditional surrender for which Allied policy called (see the Potsdam Proclamation). Intense bombing of Japan (on March 9-10, 1945, for example, bombs leveled nearly 16 square miles of Tokyo and killed 90,000 Japanese) had not moved Japan to surrender. Continued fighting in the Pacific (Iwo Jima, February-March, 1945; Okinawa, April-June 1945; and ongoing fighting in the Philippines) led to mounting American casualties. The experience of the invasion of Normandy June 4, 1944 also informed decision making about the use of the atomic bomb.

In May of 1945, Secretary of War Stimson set up a committee, the Interim Committee, to consider issues arising from the development of usable nuclear energy. The Interim Committee was chaired by Brigadier General Leslie Groves and J. Robert Oppenheimer, the two who led the Manhattan Project that developed the atomic bomb. Among other things, this committee considered whether and how the atomic bomb should be used. A sub-committee consisting of scientists involved in the bomb project reported on this question on June 16, 1945. The Interim Committee recommended to Stimson on June 21 “that the weapon be used against Japan at the earliest opportunity, that it be used without warning, and that it be used on a dual target, namely, a military installation or war plant surrounded by or adjacent to homes or other buildings most susceptible to damage.”

On June 18, 1945, President Truman met with his civilian and military advisers to consider the plan for the invasion of Japan. At the subsequent Potsdam Conference, Truman and Allied leaders warned Japan of the consequences of further resistance.

On August 6, 1945, the United States dropped an atomic bomb on Hiroshima, Japan, killing 80,000 people instantly. The American people learned about the new weapon from a White House press release. Three days later, the United States dropped a second atomic bomb on Nagasaki that killed 35,000 people. Japan surrendered unconditionally on August 14. Devastating though these attacks were, the bombing of Hiroshima and Nagasaki was not the only factor that led the Japanese to surrender unconditionally. A blockade had fully isolated Japan from outside resources by the summer of 1945 and the Russians entered the war against Japan, August 9, 1945. The latter event was a factor considered on June 18.

Shortly after the first use of the bomb, Oppenheimer wrote to Secretary of War Stimson to express his growing concern, shared by many of the scientists who worked on the Manhattan Project, about the military and political consequences of atomic weapons.

Michael B. Stoff et al., eds., The Manhattan Project: A Documentary Introduction to the Atomic Age (Philadelphia: Temple University Press, 1991), 150. Available at The Atomic Bomb and the End of World War II, The National Security Archive.

You have asked us to comment on the initial use of the new weapon. This use, in our opinion, should be such as to promote a satisfactory adjustment of our international relations. At the same time, we recognize our obligation to our nation to use the weapons to help save American lives in the Japanese war.

(1) To accomplish these ends we recommend that before the weapons are used not only Britain, but also Russia, France, and China be advised that we have made considerable progress in our work on atomic weapons, and that we would welcome suggestions as to how we can cooperate in making this development contribute to improved international relations.

(2) The opinions of our scientific colleagues on the initial use of these weapons are not unanimous: they range from the proposal of a purely technical demonstration to that of the military application best designed to induce surrender. Those who advocate a purely technical demonstration would wish to outlaw the use of atomic weapons, and have feared that if we use the weapons now our position in future negotiations will be prejudiced. Others emphasize the opportunity of saving American lives by immediate military use, and believe that such use will improve the international prospects, in that they are more concerned with the prevention of war than with the elimination of this specific weapon. We find ourselves closer to these latter views; we can propose no technical demonstration likely to bring an end to the war; we see no acceptable alternative to direct military use.

(3) With regard to these general aspects of the use of atomic energy, it is clear that we, as scientific men, have no proprietary rights. It is true that we are among the few citizens who have had occasion to give thoughtful consideration to these problems during the past few years. We have, however, no claim to special competence in solving the political, social, and military problems which are presented by the advent of atomic power.

Study Questions

A. When discussing bringing the war against Japan to a close, what factors did President Truman and his military and civilian advisers consider? Did their concerns differ from those of the committee of scientists who offered advice on when and how to use the bomb? How might these different considerations have affected the decision to use the bomb? Should the points made in Oppenheimer’s letter have led to the decision not to drop the bomb? Is the advice given in by report of the Interim Committee scientific advice? Why should anyone have listened to it?

B. Based on the documents concerning Progressive advocacy of eugenics and the documents on the atomic bomb, what is the proper relationship between science and politics? Does politics control science or does science control politics?

C. What do both the dropping of the atomic bomb and President Washington’s decision to call out the militia to end the Whiskey Rebellion tell us about the evolving understanding of executive power in the United States?