This Day In History Sep 21, 1942 The Superfortress takes flight On this day in 1942, the U.S. B-29 Superfortress makes its debut flight in Seattle, Washington. It was the largest bomber used in the war by any nation. The B-29 was conceived in 1939 by Gen. Hap Arnold, who was afraid a German victory in Europe would mean the United States would be devoid of bases on the eastern side of the Atlantic from which to counterattack. A plane was needed that would travel faster, farther, and higher than any then available, so Boeing set to creating the four-engine heavy bomber. The plane was extraordinary, able to carry loads almost equal to its own weight at altitudes of 30,000 to 40,000 feet. It contained a pilot console in the rear of the plane, in the event the front pilot was knocked out of commission. It also sported the first radar bombing system of any U.S. bomber. The Superfortress made its test run over the continental United States on September 21, but would not make its bombing-run debut until June 5, 1944, against Bangkok, in preparation for the Allied liberation of Burma from Japanese hands. A little more than a week later, the B-29 made its first run against the Japanese mainland. On June 14, 60 B-29s based in Chengtu, China, bombed an iron and steel works factory on Honshu Island. While the raid was less than successful, it proved to be a morale booster to Americans, who were now on the offensive. Meanwhile, the Marianas Islands in the South Pacific were being recaptured by the United States, primarily to provide air bases for their new B-29s—a perfect position from which to strike the Japanese mainland on a consistent basis. Once the bases were ready, the B-29s were employed in a long series of bombing raids against Tokyo. Although capable of precision bombing at high altitudes, the Superfortresses began dropping incendiary devices from a mere 5,000 feet, firebombing the Japanese capital in an attempt to break the will of the Axis power. One raid, in March 1945, killed more than 80,000 people. But the most famous, or perhaps infamous, use of the B-29 would come in August, as it was the only plane capable of delivering a 10,000-pound bomb—the atomic bomb. The Enola Gay and the Bock's Car took off from the Marianas, on August 6 and 9, respectively, and flew into history.