U.S. atomic bombing of Hiroshima on August 6, 1945: scale and legacy

On the morning of August 6, 1945, a crew from Tinian Island flew the B-29 Enola Gay over Hiroshima and dropped the uranium device known as “Little Boy,” the first atomic weapon used in combat. The bomb, measuring 10 feet and weighing 9,788 pounds, detonated at roughly 1,900 feet altitude, producing a fireball 900 feet across and a mushroom cloud that rose about 20,000 feet. The blast leveled 5 square miles, razed 62,000 buildings, and instantly killed as many as 80,000 people; the City of Hiroshima later reported an estimated 140,000 deaths by the end of 1945, with the Department of Energy noting nearly 200,000 deaths over five years.

President Harry Truman, having learned of the Manhattan Project, ordered the bombing after Japan rejected the Potsdam Declaration and prepared for a costly invasion. The devastation contributed to Japan’s decision to surrender on August 14, bringing World War II to a close.