The United States dropped the Fat Man atomic bomb on Nagasaki on 9 August 1945.
The weapon was carried by the B-29 bomber Bockscar and detonated over Nagasaki during the morning. Fat Man was a plutonium implosion weapon, unlike Little Boy, the uranium gun-type bomb used against Hiroshima three days earlier.
The mission took place on the same date that the Soviet Union declared war on Japan and began its invasion of Japanese-held Manchuria. Japanese leaders therefore faced both the second atomic bombing and the collapse of their hope that Moscow might mediate a better peace.
Fat Man’s date is often mixed up with 6 August, the date of the Hiroshima bombing, or 15 August, the date of the emperor’s public surrender broadcast. All three dates belong to different events.