美國歷史上的今天

曼哈頓計劃

When: April 24, 1945

What: President Harry S. Truman was briefed on Manhattan Project, in which scientists were attempting to create the first atomic bomb. 

Why significant: Although the war in Europe ended in May 1945, Truman was advised that the bomb might be useful in intimidating Soviet leader Joseph Stalin into curtailing post-war communist expansion into Eastern Europe. Truman agreed. 

Meanwhile the war with Japan continued, and it seemed that an invasion of Japan might be necessary to force the Japanese to surrender. But such a ground war would result in many deaths on both sides. Truman believed that using the atomic bombs would shorten the war and thereby save the lives of hundreds of thousands of American soldiers and Japanese soldiers and citizens. So after receiving no reply to his threat that "prompt and utter destruction" would follow if the Japanese did not surrender unconditionally, Truman authorized the use of the bomb on Japan. The first bomb was exploded over Hiroshima on August 6, 1945, and a second was dropped on Nagasaki on August 8. The bombing killed 210,000 people. The Japanese quickly surrendered. 

Truman's decision to use atomic bombs remains controversial, as some people question whether the U.S. might have been able to gain Japan’s unconditional surrender by other means, and whether the use of atomic bombs was necessary. But there was no question that the development and use of the atomic bomb changed the nature of world warfare forever. Though the bombings of Japan remain the only wartime use of nuclear weapons, since 1945 the threat of nuclear war has loomed over international conflicts, promising a level of "prompt and utter destruction" never before seen in the world.

Tags: Manhattan Project, WW II, President Harry S. Truman