The United States dropped the atomic bomb on Nagasaki on August 9, 1945.
The B-29 bomber Bockscar released the plutonium implosion weapon known as Fat Man over Nagasaki. The bombing followed the destruction of Hiroshima by the uranium bomb Little Boy on August 6. Nagasaki was the second Japanese city attacked with an atomic bomb.
Japan’s leadership was already facing a military and diplomatic crisis. The Soviet Union declared war on Japan on August 8, and the Nagasaki bombing occurred the following day. Historians continue to debate how these events individually and together influenced Japan’s decision, but both were part of the rapidly changing circumstances before the surrender announcement.
Emperor Hirohito announced Japan’s acceptance of the Potsdam Declaration on August 15. The formal surrender document was not signed until September 2, so the Nagasaki bombing did not itself mark the end of the war. The date is also distinct from August 6, the date of the Hiroshima bombing.