509th Composite Group

The 509th Composite Group (509 CG) was a unit of the United States Army Air Forces created during World War II and tasked with the operational deployment of nuclear weapons. It conducted the atomic bombings of Hiroshima and Nagasaki, Japan, in August 1945.

The group was activated on 17 December 1944 at Wendover Army Air Field, Utah. It was commanded by Lieutenant Colonel Paul W. Tibbets. Because it contained flying squadrons equipped with Boeing B-29 Superfortress bombers, C-47 Skytrain, and C-54 Skymaster transport aircraft, the group was designated as a "composite", rather than a "bombardment" formation. It operated Silverplate B-29s, which were specially configured to enable them to carry nuclear weapons.

The 509th Composite Group began deploying to North Field on Tinian, Northern Mariana Islands, in May 1945. In addition to the two nuclear bombing raids, it carried out 15 practice missions against Japanese-held islands, and 12 combat missions against targets in Japan dropping high-explosive pumpkin bombs.

In the postwar era, the 509th Composite Group was one of the original ten bombardment groups assigned to Strategic Air Command on 21 March 1946 and the only one equipped with Silverplate B-29 Superfortress aircraft capable of delivering atomic bombs. It was standardized as a bombardment group and redesignated the 509th Bombardment Group, Very Heavy, on 10 July 1946.