Nagasaki was struck by the second atomic bomb before Japan’s surrender in 1945. The United States dropped the plutonium bomb known as Fat Man on August 9, three days after the bombing of Hiroshima.
The Nagasaki attack occurred on the same day the Soviet Union declared war on Japan. The original target for the mission was Kokura, but poor visibility led the bomber crew to proceed to the secondary target, Nagasaki. The bomb detonated over the city’s Urakami Valley, where factories and other industrial facilities were located.
Japan’s leaders faced several simultaneous shocks in August 1945: the destruction of Hiroshima, the Soviet invasion of Japanese-held territory, the threat of further attacks, and the breakdown of hopes that Moscow might mediate. Emperor Hirohito intervened in the surrender decision, and Japan announced acceptance of the Potsdam Declaration on August 15. The formal surrender followed aboard USS Missouri on September 2.