Hiroshima was the target of the atomic bomb named Little Boy in August 1945.
The United States dropped Little Boy over Hiroshima on August 6, 1945. The weapon was carried by the B-29 bomber Enola Gay and detonated at approximately 8:15 a.m. local time. It was the first use of a nuclear weapon in warfare.
Little Boy used a uranium-235 gun-type design. Its mechanism differed from Fat Man, the plutonium implosion weapon dropped on Nagasaki three days later. Hiroshima was selected because it contained military facilities and had not been as heavily damaged by earlier conventional bombing, making the effects easier to assess.
The bombing caused catastrophic destruction and mass death. Radiation exposure also produced severe long-term health consequences. Japan did not surrender immediately after Hiroshima; the Soviet declaration of war and the Nagasaki bombing followed before the final surrender decision was announced.