The United States used two atomic bombs against Japan before its 1945 surrender.
The first bomb, nicknamed Little Boy, was dropped on Hiroshima on August 6, 1945. The second, nicknamed Fat Man, was dropped on Nagasaki on August 9. These were the only wartime uses of nuclear weapons against cities.
The bombings caused immense destruction and loss of life, although exact death totals remain difficult to determine because many victims later died from injuries and radiation exposure. The attacks were followed closely by the Soviet declaration of war and invasion of Japanese-held Manchuria.
Historians continue to debate the relative importance of the atomic bombings, the Soviet entry, Japan’s military situation, and internal political divisions in the surrender decision. The immediate historical sequence is clear: the two bombings occurred within three days, and Japan announced its acceptance of the Allied terms on August 15.