The atomic bomb dropped on Nagasaki during the final weeks of World War II was called Fat Man.
Fat Man was a plutonium-based implosion weapon dropped on August 9, 1945. It was carried by the B-29 bomber Bockscar after the crew could not make a visual attack on Kokura, the primary target. Nagasaki became the secondary target.
The bomb exploded over the Urakami Valley at about 11:02 a.m. local time. Its design differed from Little Boy, the uranium gun-type weapon used against Hiroshima three days earlier. The names referred to the bombs’ shapes and design concepts rather than to their targets.
The bombings occurred alongside the Soviet declaration of war on Japan and invasion of Japanese-held territory in Manchuria. Japan announced its acceptance of the Allied surrender terms several days later.