Bockscar had been built at the Glenn L. Martin Aircraft Plant at Omaha, Nebraska, as a block 35 aircraft. It was one of the 10 B-29 aircraft modified as a Silverplate and re-designated "Block 36". On March 19, 1945, it had been delivered to the US Army Air Corps, and assigned to Capt. Frederick C. Bock and crew C-13, from the 393rd Bomb Squadron of the 509th Composite Group. Then the Bockscar had been flown to Wendover Army Air Field, Utah.

The original pilot and commander of the Bockscar was Captain Frederick C Bock, but on August 9, 1945, for the Nagasaki bombing mission, it was flown by the B-29 Great Artiste’s crew (crew-15), whose commander was Charles W Sweeney. The main target for the August 9 mission was the Japanese city of Kokura, but because of poor visibility due to a clouds cover, Charles Sweeney decided to drop the bomb on Nagasaki instead.

Bockscar was also used in several training and practice missions from Tinian, and three combat missions in which it dropped pumpkin bombs on industrial targets in Japan. Bock’s crew bombed Niihama and Musashino, and 1st Lt. Don Albury and crew C-15 bombed Toyama. In November 1945, it returned to the United States, serving with the 509th Composite Group at Roswell Army Air Field, New Mexico. In August 1946, Bockscar was assigned to the 4105th Base Unit at Davis-Monthan Army Air Field, Arizona, for storage.

Albury was born in Miami, Florida, on October 12, 1920. Although he had enrolled at the University of Miami’s engineering school, Albury dropped out before he finished his bachelor’s degree. The reason for this is that he wanted to enlist in the United States Army during World War II. Having trained as a pilot in the US Army Air Corps, Charles Albury was selected to join the 509th Composite Group in 1943. The 509th Composite Group also included Col. Paul Tibbets, who would later command the Enola Gay during the atomic bombing of Hiroshima. As part of the Composite Group, both Albury and Tibbets trained at the Wendover Air Force Base, located in Utah. But they did not know what they were training so hard for.

On August 6, 1945, Albury was the co-pilot of the instrument observation B-29 plane, known as The Great Artiste, which escorted the B-29 Enola Gay commanded by Tibbets. On August 6, his job for the Hiroshima mission was to drop instrumentation to record the magnitude of the bomb blast and the radioactivity. When Tibbets dropped the bomb, the Great Artiste dropped the instruments.

Three days after the bombing of Hiroshima, Albury was selected to co-pilot the B-29 Superfortress, "Bockscar", which would drop the atomic bomb known as the "Fat Man" on the city of Nagasaki. The Bockscar was piloted by Major Charles Sweeney. The original target for the August 9 mission was the city of Kokura, but this target was was not sighted and skipped due to cloud cover until the crew located a hole in the clouds. The Bockscar dropped the 10,200-pound "Fat Man" on the city of Nagasaki, instead.

Charles Sweeney was born in Lowell, Massachusetts, on December 27, 1919. His father was a plumber. Sweeney began flying while attending North Quincy High School. Having graduated from High School in 1937, he attended classes at Boston University and Purdue University. In April 1941, he enlisted as an aviation cadet in the U.S. Army Air Corps. When he received his pilot wings and a commission as a second lieutenant, Sweeney trained for two years at the Jefferson Proving Ground in Indiana. In 1944 he was promoted to major and assigned as a B-29 Superfortress pilot instructor at Grand Island Army Airfield, Nebraska.

Sweeney spent most of the war as an instructor and test pilot. He was selected to be part of the 509th Composite Group, under the command of Col. Paul Tibbets, and was named commander of the 320th Troop Carrier Squadron on January 6, 1945. At the beginning his squadron used C-47 Skytrain and C-46 Commando transports on hand to conduct the top secret operations to supply the 509th, but in April 1945 it received five C-54 Skymasters, which had the range to deliver personnel and materiel to the western Pacific area.

On August 6, 1945, Sweeney piloted B-29 The Great Artiste, which was the instrumentation support aircraft of the B-29 Enola Gay, which dropped the atomic bomb on Hiroshima. On August 9, 1945, Major Sweeney commanded the B-29 Bockscar, which dropped Fat Man on Nagasaki. On the August 9 mission the main target of the atomic atack was Kokura, but Sweeney had to change course because of bad weather conditions and headed for Nagasaki. The Bockscar dropped a plutonium weapon with a blast yield equivalent to 21 kilotons of TNT. Approximately 70,000 people were killed in the initial explosion and 60% of Nagasaki was destroyed. Japan surrendered six days after the bombing.

After the Second World War, the 509th Composite Group was one of the original ten USAAF bombardment groups assigned to Strategic Air Command on March 21, 1946. It was equipped with specially-configured B-29 Superfortress modified to deliver atomic Bombs. On July 10, 1946, the Composite Group was redesignated the 509th Bombardment Group. Because the flying squadrons of the group consisted of both bomber and transport aircraft, the group was designated as a "composite" rather than a "bombardment" unit.

Enola Gay was built by the Glenn L. Martin Company at its Bellevue plant in Nebraska. It was one of fifteen B-29s with the Silverplate modifications necessary to deliver atomic weapons. Enola Gay serial number was 44-86292, victor number 82 and was assigned to the USAAF’s 393d Bombardment Squadron, Heavy, 509th Composite Group. It was personally selected by Colonel Paul W. Tibbets, Jr., commander of the 509th Composite Group, on May 9, 1945, while still on the assembly line. This would be the B-29 which would be used to fly the atomic bomb mission.

On August 6, 1945, the Enola Gay was escorted by two other B-29s: Necessary Evil and The Great Artiste. The former was used as a camera plane to photograph the explosion and effects of the bomb and carry scientific observers; the latter was the blast measurement instrumentation aircraft. Although it was originally given the victor number 12, on August 1 it was given the circle R tail markings of the 6th Bomb Group as a security measure and had its victor changed to "82" to avoid misidentification with actual 6th BG aircraft.

Enola Gay’s crew was composed of twelve men, who were not the original crew. They had been specially selected for the atomic bomb mission.