Nagasaki was the target of the second atomic bomb before the surrender announcement.
The United States dropped an atomic bomb on Nagasaki on August 9, 1945. The attack followed the bombing of Hiroshima three days earlier and occurred on the same day that the Soviet Union declared war on Japan and invaded Japanese-held Manchuria. These events intensified the crisis facing Japan’s leaders.
The Nagasaki weapon was a plutonium implosion bomb known as Fat Man. It detonated over the Urakami Valley and caused extensive destruction and loss of life. Nagasaki had been an important industrial and port city, with factories connected to shipbuilding and armaments.
Emperor Hirohito announced Japan’s acceptance of the Potsdam Declaration on August 15. Historians continue to debate the relative importance of the atomic bombings, the Soviet entry into the war, and other factors in Japan’s decision. The formal surrender was signed later, on September 2, aboard USS Missouri.