Hiroshima was targeted by the first atomic bomb used in World War II.
The United States dropped the uranium bomb nicknamed Little Boy over Hiroshima on 6 August 1945. The weapon detonated at approximately 8:15 a.m. local time, destroying much of the city and causing enormous civilian casualties.
Hiroshima was a military headquarters and an important transportation and industrial center. It had not previously experienced the level of conventional bombing inflicted on many other Japanese cities, which helped American planners assess the atomic weapon's effects.
Japan did not surrender immediately after Hiroshima. The Soviet Union declared war on Japan and invaded Manchuria on 9 August, the same day the United States dropped a second atomic bomb on Nagasaki. Hirohito announced Japan's surrender on 15 August.