Hiroshima was the first city struck by an atomic bomb in August 1945, before Japan surrendered.
The United States dropped the uranium gun-type bomb Little Boy over Hiroshima on August 6, 1945. The bomb detonated at approximately 8:15 a.m. local time, causing catastrophic destruction across the city and killing or fatally injuring a very large number of people.
Hiroshima was an important military and industrial center, and much of the central city was built on relatively flat terrain. The blast, heat, fires, and radiation devastated buildings and civilians. The bombing became one of the decisive events in the final days of World War II.
Nagasaki was bombed three days later, on August 9, with the plutonium implosion weapon Fat Man. Japan’s surrender decision also followed the Soviet declaration of war and invasion of Manchuria, so historians discuss several interacting causes rather than one universally accepted explanation.