th Reflections on the 70 Anniversary of the Manhattan Project: Questions and Answers Reflections on the 70th Anniversary of the Manhattan Project: Questions and Answers By B. Cameron Reed I began my professional life by obtaining degrees in physics and entering a conventional academic career in teaching and astronomical research, but I had always been curious about the physics of the Manhattan Project and its role in ending World War II. With grants, publications and tenure established, I began to indulge this interest as a legitimate part of my work and about 20 years ago, to explore it in depth. As anybody that comes to this topic in more than a casual way will attest, it can grow into an obsession. I have now published two books on the Project, well over two dozen articles and book reviews in technical, historical, and semi-popular journals, and have made a number of presentations at professional conferences. Over this time I must have looked at thousands of archived documents and held hundreds of real and electronic conversations with other scientists, historians, and writers whose interest in this pivotal event parallels my own. While my knowledge of the Project is certainly not and never will be complete, I have learned much about it over the last 20 years. To my surprise (and pleasure) I am frequently asked questions about the Project by students, family members, guests at dinner parties, colleagues at American Physical Society meetings, and even casual acquaintances at my favorite coffee shop. Typical queries are: “Why did we drop the bombs? Were they necessary to end the war?” “Did President Truman and his advisors really understand the power of the bombs and the destruction they could cause?” “Have nuclear weapons helped deter subsequent large-scale wars, and do we still need a deterrent?” “What about the ethical aspects?” “In studying the Manhattan Project, what most surprised you? Do you think it or something similar could be done now?” At first I was awkward in trying to answer these questions but with passing years, increased knowledge, and much reflection I now feel more comfortable addressing them. With accumulating experience in a scientific career, you often learn that the questions you and others initially thought to Federation of American Scientists | Public Interest Report | Winter 2015– Volume 68 Number 1 th Reflections on the 70 Anniversary of the Manhattan Project: Questions and Answers be important may not be the ones that the facts address and that there may be much more interesting issues behind the obvious ones. In this spirit, I offer in this essay some very personal reflections on the Project and the legacies of Hiroshima and Nagasaki, framed as responses to questions like those above. In some cases a “yes” or “no” along with an explanation will do, but for many issues the nuances involved obviate a simple response. I begin with the issue of the “decision” to use the bomb and the state of President Truman’s knowledge. In the spring of 1945, Secretary of War Henry Stimson assembled a committee to consider and advise upon immediate and long-term aspects of atomic energy. This “Interim Committee” comprised eight civilians, including three scientists intimately familiar with the Manhattan Project: Vannevar Bush, James Conant, and Karl Compton. In a meeting on May 31 which was attended by Army Chief of Staff General George C. Marshall, Stimson opened with a statement as to how he viewed the significance of the Project1: The Secretary expressed the view, a view shared by General Marshall, that this project should not be considered simply in terms of military weapons, but as a new relationship of man to the universe. This discovery might be compared to the discoveries of the Copernican theory and of the laws of gravity, but far more important than these in its effect on the lives of men. While the advances in the field to date had been fostered by the needs of war, it was important to realize that the implications of the project went far beyond the needs of the present war. It must be controlled if possible to make it an assurance of future peace rather than a menace to civilization. For his part, President Truman had been thoroughly briefed on the project by Stimson and General Leslie Groves, director of the Project, soon after he became President in late April. In late July, Truman recorded his reaction to the Trinity test in his diary2: We have discovered the most terrible bomb in the history of the world. ... Anyway we think we have found the way to cause a disintegration of the atom. An experiment in the New Mexico desert was startling - to put it mildly. Thirteen pounds of the explosive caused the complete disintegration of a steel tower 60 feet high, created a crater 6 feet deep and 1,200 feet in diameter, knocked over a steel tower 1/2 mile away and knocked men down 10,000 yards away. The explosion was visible for more than 200 miles and audible for 40 miles and more. ... The target will be a purely military one and we will issue a warning statement asking the Japs 1 Minutes of Interim Committee meetings can be found at https://www.nuclearfiles.org/menu/key-issues/nuclear-weapons/history/pre- cold-war/interim-committee/interim-committee-informal-notes_1945-05-31.htm 2 R.H. Ferrell, Harry S. Truman and the Bomb. High Plains Publishing Co., Worland, WY (1996), p. 31 Federation of American Scientists | Public Interest Report | Winter 2015– Volume 68 Number 1 th Reflections on the 70 Anniversary of the Manhattan Project: Questions and Answers to surrender and save lives. I’m sure they will not do that, but we will have given them the chance. It is certainly a good thing for the world that Hitler’s crowd or Stalin’s did not discover this atomic bomb. It seems to be the most terrible thing ever discovered, but it can be made the most useful... I have no doubt that Stimson, Marshall and Truman were well aware of the revolutionary nature of the bomb and the possibility (indeed, likelihood) that a postwar nuclear arms race would ensue. Any notion that Truman was a disengaged observer carried along by the momentum of events is hard to believe in view of the above comments. These men were making decisions of grave responsibility and were fully briefed as to both the immediate situation of the war and possible long-term geopolitical consequences: the “mature consideration” that Franklin Roosevelt and Winston Churchill agreed in 1943 would have to be carried out before use of the bombs was authorized. Perhaps Truman did not so much make a positive decision to use the bombs so much as he opted not to halt operations that were already moving along when he became President, but I have no doubt that he realized that atomic bombs would be a profoundly new type of weapon. Further, let us not forget that it was Truman who personally intervened after Nagasaki to order a halt to further atomic bombings when the Japanese began to signal a willingness to consider surrender negotiations. As much as I am convinced that Truman took his duties with the greatest sense of responsibility, I cannot answer “yes” or “no” as to the necessity of the bombings: the question is always loaded with so many unstated perspectives. If the Japanese could not be convinced to surrender, then Truman, Stimson, and Marshall faced the prospect of committing hundreds of thousands of men to a horrific invasion followed by a likely even more horrific slog through the Japanese home islands. After 70 years it is easy to forget the context of the war in the summer of 1945. Historians know that the Japanese were seeking a path to honorable surrender and might have given up within a few weeks, but the very bloody fact on the ground was that they had not yet surrendered; thousands of Allied and Japanese servicemen were dying each week in the Pacific. Military historian Dennis Giangreco has studied Army and War Department manpower projections for the two-part invasion of Japan scheduled for late 1945 and the spring of 19463. Planning was based on having to sustain an average of 100,000 casualties per month from November 1945 through the fall of 1946. The invasion of Kyushu was scheduled to begin on November 1, 1945. Had this occurred, the number of casualties might well have exceeded the number of deaths at Hiroshima and Nagasaki, let alone those which would have occurred in the meantime. From the perspective of preventing casualties, perhaps it was unfortunate 3 D. M. Giangreco, “Casualty Projections for the U. S. Invasion of Japan, 1945-1946: Planning and Policy Implications.” Journal of Military History 61, 521-582 (1997). Federation of American Scientists | Public Interest Report | Winter 2015– Volume 68 Number 1 th Reflections on the 70 Anniversary of the Manhattan Project: Questions and Answers that the bombs were not ready at the time of the battle for Iwo Jima, one of the bloodiest protracted battles from February 19 to March 26, 1945, during which more than 25,000 were killed on both sides. Even if they believe that the Soviet Union’s declaration of war on the night of August 8, 1945, against Japan was the most significant factor in the Japanese decision to surrender, most historians allow that the bombs had at least some effect on that decision. The Soviet invasion came between the two atomic bombings on August 6 (Hiroshima) and August 9 (Nagasaki).