Little Boy was the first atomic bomb used in warfare, dropped on Hiroshima on 6 August 1945.
The uranium gun-type weapon was carried by the B-29 bomber Enola Gay, piloted by Colonel Paul Tibbets. It detonated over Hiroshima at approximately 8:15 a.m. local time. Little Boy was not tested in a full-scale nuclear explosion before combat use because its design was considered sufficiently predictable and enriched uranium was scarce.
Little Boy is often confused with Fat Man, the plutonium implosion bomb dropped on Nagasaki three days later. Thin Man was an earlier plutonium gun-type design abandoned during development, while “The Gadget” was the device tested at Trinity in July 1945.
The bombings, the Soviet entry into the war, and Japan’s internal political crisis contributed to the surrender announcement on 15 August. The precise role of each factor remains debated by historians.