Bockscar carried the atomic bomb used against Nagasaki on August 9, 1945.
The B-29 was flown by Major Charles W. Sweeney from Tinian in the Mariana Islands. Its bomb, Fat Man, was a plutonium implosion weapon. Nagasaki was the mission’s secondary target because heavy cloud and smoke obscured Kokura, the primary target, after several bombing passes. Bockscar therefore diverted to Nagasaki and released the weapon there.
Bockscar’s mission occurred three days after Enola Gay dropped Little Boy on Hiroshima. The Soviet Union also declared war on Japan during this period, attacking Japanese forces in Manchuria. Japan’s leadership debated surrender before Emperor Hirohito intervened in favor of accepting the Potsdam Declaration. Bockscar is sometimes incorrectly identified as the Hiroshima aircraft; Enola Gay performed that earlier mission, while Bockscar carried out the second atomic bombing.