Wendover Army Air Field in the context of "509th Composite Group"

Bockscar, sometimes called Bock's Car, is the United States Army Air Forces Boeing B-29 Superfortress bomber that dropped a Fat Man atomic bomb over the Japanese city of Nagasaki during World War II in the second – and most recent – nuclear attack in history. One of 15 Silverplate B-29s used by the 509th, Bockscar was built at the Glenn L. Martin Bomber Plant at Bellevue, Nebraska, at what is now Offutt Air Force Base, and delivered to the United States Army Air Forces on 19 March 1945. It was assigned to the 393rd Bombardment Squadron, 509th Composite Group to Wendover Army Air Field, Utah, in April and was named after captain Frederick C. Bock.

Bockscar was used in 13 training and practice missions from Tinian, and three combat missions in which it dropped pumpkin bombs on industrial targets in Japan. On 9 August 1945, Bockscar, piloted by the 393rd Bombardment Squadron's commander, Major Charles W. Sweeney, dropped a Fat Man nuclear bomb with a blast yield equivalent to 21 kilotonnes of TNT (88 TJ) over the city of Nagasaki. The explosion destroyed about 44% of the city, killed 35,000 people, and injured 60,000 people.