The Dropping of the Atomic Bombs on Japan On August 6, 1945 the United States exploded an atomic bomb over Hiroshima and revealed to the world in one blinding flash the start of the atomic age. The decision to use the atomic bomb was made by President Truman. There was never any doubt of that and despite the rising tide of criticism, Mr. Truman took full responsibility for his action. The final decision was his and his alone. [1] The story of the development of the atomic bomb is well known throughout the world. It began in 1939 when a small group of scientists in this country called to the attention of the United States Government the vast potentialit