Bockscar, a specially modified Silverplate Boeing B-29 Superfortress of the United States Army Air Forces, carried the Fat Man atomic bomb on the attack on Nagasaki on 9 August 1945, the second and most recent wartime use of a nuclear weapon. Flown that day by Major Charles W. Sweeney's crew after weather and mechanical problems disrupted the mission, it diverted from Kokura to Nagasaki and dropped the bomb over the Urakami Valley, devastating much of the city and causing massive casualties. After a fuel-starved emergency landing on Okinawa and postwar service, the aircraft was preserved and is now displayed at the National Museum of the United States Air Force.