Hiroshima was the first Japanese city hit by an atomic bomb in World War II.
The United States dropped the uranium gun-type bomb known as Little Boy over Hiroshima on August 6, 1945. The bomb exploded at approximately 8:15 a.m. local time, devastating much of the city and killing tens of thousands of people immediately or soon afterward.
Hiroshima had been selected as a target because it was a substantial urban center with military facilities and had not suffered the same level of conventional bombing as several other Japanese cities. The attack demonstrated the destructive power of the new weapon to Japanese officials and the wider world.
Nagasaki was struck three days later, on August 9, by the plutonium implosion bomb Fat Man. Hiroshima was therefore the first atomic-bomb target in wartime history, while Nagasaki became the second and, as of 2026, the last city attacked with a nuclear weapon in war.