Nagasaki was the target of the second atomic bomb used against Japan before its surrender.
The United States dropped the plutonium implosion bomb known as Fat Man on Nagasaki on August 9, 1945. The bombing followed the atomic bombing of Hiroshima three days earlier. Nagasaki contained major industrial and military facilities, including shipbuilding and arms production.
The attack occurred during a rapidly changing strategic and political crisis. On the same day, the Soviet Union entered the war against Japan and invaded Japanese-held territory in Manchuria. Japan’s leaders debated surrender while facing the atomic attacks, Soviet intervention, and the possibility of invasion.
Nagasaki was not the original primary target for the August 9 mission. Kokura had been designated the main target, but cloud cover and smoke prevented a clear view, so the aircraft proceeded to its secondary target, Nagasaki. Japan announced acceptance of the Potsdam Declaration on August 15.