Bockscar dropped the atomic bomb codenamed Fat Man on Nagasaki on August 9, 1945.
Bockscar was a Boeing B-29 Superfortress operated by the 393rd Bombardment Squadron. Major Charles W. Sweeney piloted the mission, and Frederick Ashworth served as the weaponeer. The plutonium implosion weapon was called Fat Man.
Kokura was the primary target, but cloud and smoke obscured the city after the aircraft made several attempts to find a clear aiming point. With fuel running low, the crew flew to the secondary target, Nagasaki. A break in the clouds allowed a visual approach, and the bomb was released over the city's industrial valley.
The earlier Hiroshima mission used the B-29 Enola Gay to drop Little Boy, a uranium gun-type weapon. Confusing Bockscar with Enola Gay is therefore a common mistake. The two aircraft carried different weapons on separate missions three days apart.