Silverplate in the context of B-29

Air warfare was a major component in all theaters of World War II and, together with anti-aircraft warfare, consumed a large fraction of the industrial output of the major powers. Germany and Japan depended on air forces that were closely integrated with land and naval forces; the Axis powers downplayed the advantage of fleets of strategic bombers and were late in appreciating the need to defend against Allied strategic bombing. By contrast, Britain and the United States took an approach that greatly emphasized strategic bombing and (to a lesser degree) tactical control of the battlefield by air as well as adequate air defenses. Both Britain and the U.S. built substantially larger strategic forces of large, long-range bombers. Simultaneously, they built tactical air forces that could win air superiority over the battlefields, thereby giving vital assistance to ground troops. The U.S. Navy and Royal Navy also built a powerful naval-air component based on aircraft carriers, as did the Imperial Japanese Navy; these played the central role in the war at sea.

On 6 and 9 August 1945, the United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki, respectively, during World War II. The aerial bombings killed 150,000 to 246,000 people, most of whom were civilians, and remain the only uses of nuclear weapons in an armed conflict. Japan announced its surrender to the Allies on 15 August, six days after the bombing of Nagasaki and the Soviet Union's declaration of war against Japan and invasion of Manchuria. The Japanese government signed an instrument of surrender on 2 September, ending the war.

In the final year of World War II, the Allies prepared for a costly invasion of the Japanese mainland. This undertaking was preceded by a conventional bombing and firebombing campaign that devastated 64 Japanese cities, including an operation on Tokyo. The war in Europe concluded when Germany surrendered on 8 May 1945, and the Allies turned their full attention to the Pacific War. By July 1945, the Allies' Manhattan Project had produced two types of atomic bombs: "Little Boy", an enriched uranium gun-type fission weapon, and "Fat Man", a plutonium implosion-type nuclear weapon. The 509th Composite Group of the U.S. Army Air Forces was trained and equipped with the specialized Silverplate version of the Boeing B-29 Superfortress, and deployed to Tinian in the Mariana Islands. The Allies called for the unconditional surrender of the Imperial Japanese Armed Forces in the Potsdam Declaration on 26 July 1945, the alternative being "prompt and utter destruction". The Japanese government ignored the ultimatum.

The Boeing B-29 Superfortress is a retired American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the Boeing B-17 Flying Fortress, the Superfortress was designed for high-altitude strategic bombing, but also excelled in low-altitude night incendiary bombing, and in dropping naval mines to blockade Japan. Silverplate B-29s dropped the atomic bombs on Hiroshima and Nagasaki, the only aircraft ever to drop nuclear weapons in combat.

One of the largest aircraft of World War II, the B-29 was designed with state-of-the-art technology, which included a pressurized cabin, dual-wheeled tricycle landing gear, and an analog computer-controlled fire-control system that allowed one gunner and a fire-control officer to direct four remote machine gun turrets. The $3 billion cost of design and production (equivalent to $52 billion in 2024), far exceeding the $1.9 billion cost of the Manhattan Project, made the B-29 program the most expensive of the war. The B-29 remained in service in various roles throughout the 1950s, being retired in the early 1960s after 3,970 had been built. A few were also used as flying television transmitters by the Stratovision company. The Royal Air Force flew the B-29 with the service name Washington from 1950 to 1954 when the jet-powered Canberra entered service.

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.

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.