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The Ultimate Weapon or the Ultimate Mistake: Should America Have Dropped Nuclear Weapons on Japan?

The most controversial decision of the 20th century—probably in all of history—was the one reportedly made by President Harry S. Truman, president of the United States and commander-in-chief of the United States armed forces, in the summer of 1945 to drop the atomic bomb on Japan. No other event has affected mankind so dramatically, and no other decision is as controversial.

To the young soldiers and Marines who were in training or moving to the Pacific when “the bomb” was dropped there was no question—many of them survived the war because Harry Truman “had the guts to drop it.” This belief was burned into their young minds when they heard the news and most never bothered to question whether it was founded on fact. In recent years their sons have sought to reinforce the belief of their fathers, once again without taking a serious look at the facts surrounding the decision to drop the bomb and the events leading up to it. Yet, in reality, Truman never made an actual decision to use the bomb, and it was the one decision made by Emperor Hirohito of Japan to accept Allied surrender terms and end the war that actually spared their lives.

Even while millions of Americans continue to believe that the atomic bomb ended World War II, many, including some in high positions in government and the military at the time, have long believed it was unnecessary. Previously classified documents released to the National Archives in recent years support their position that the White House knew the end for Japan had already come and that the use of atomic weapons was motivated more by postwar concerns than by preventing an amphibious invasion of Japan. Furthermore, principals such as General Leslie Groves, the officer in charge of the nuclear project, have revealed that there never really was a “decision” as such by President Truman to drop the bomb, but that he simply allowed plans that were already in motion before he was thrust into office to continue. In essence, the decision to use atomic weapons against Japan was made long before Truman even had an inkling of their existence.

Building the Bomb

American research into the possibility of creating powerful weapons using nuclear fission actually predated the outbreak of World War II by several weeks. In July 1939, three European scientists met with renowned physicist Albert Einstein and persuaded him to write a letter to President Franklin D. Roosevelt advising that a bomb designed to produce a nuclear explosion might be under development in Germany. Einstein’s letter is dated August 2, 1939, nearly a month before Germany and the Soviet Union invaded Poland and World War II officially began. British scientists were already working on such a weapon, and the United States began a similar, although generally unsuccessful, effort in response to the Einstein letter.ƒ

In 1941, a group of American scientists visited England, where considerable nuclear research work was being done. Prior to the visit, no American scientist believed that nuclear fission would be of critical importance to the war, but the British work so impressed the visitors that in December they recommended that a full-scale nuclear project commence in the United States. President Roosevelt authorized a research program under the code name Manhattan Engineering Project, and British nuclear experts came to the United States to work with their American counterparts in research toward the development of a nuclear weapon.

In September 1942, the War Department assumed control of the project and Colonel Leslie R. Groves of the Army Corps of Engineers, who had previously been in charge of the construction of the Pentagon, was appointed as the project head. On December 2, 1942, Dr. Enrico Fermi, an Italian-born physicist working at the University of Chicago, achieved fission, the first controlled release of nuclear energy. Fermi’s successful experiment proved that it was indeed possible to develop a nuclear weapon and ushered the world into the nuclear age. The next step was to develop a means of maintaining the nuclear material in an inert state until the desired detonation point.

Manhattan Project scientists solved the problem by dividing nuclear material into two masses, then firing one into the other to achieve an explosion. Another method was to place the nuclear material between two masses of conventional explosives. The shock waves of their detonation would cause the plutonium to collapse and then expand again in a powerful explosion. The first method was used for the bomb dropped on Hiroshima, while the second was the mechanism for the first nuclear detonation at the Trinity site in New Mexico and in the bomb dropped on Nagasaki. The nuclear secret was so classified that President Roosevelt did not even inform his vice presidents of it. (Truman was the third of three vice presidents who served with Roosevelt. Truman was not elected until November 1944 and did not take the vice-presidential office until the following January, only a few weeks before FDR’s death.)

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