Hiroshima was the first Japanese city targeted by an atomic bomb in August 1945.
The United States dropped the uranium gun-type bomb Little Boy over Hiroshima on August 6, 1945, at approximately 8:15 a.m. local time. The bombing destroyed much of the city and caused massive civilian casualties, both immediately and through later radiation effects.
Three days later, on August 9, the United States dropped the plutonium implosion bomb Fat Man on Nagasaki. The two attacks, together with the Soviet Union's entry into the war against Japan, preceded Japan's acceptance of the Allied surrender terms.
Kokura was the primary target for the second mission but was obscured by weather and smoke, so the aircraft proceeded to Nagasaki. Kyoto was removed from the target list before the attacks.