Nagasaki was the secondary target of the August 9, 1945 atomic bombing.
The B-29 bomber Bockscar carried the plutonium weapon Fat Man on the mission. Kokura was the primary target, but cloud cover and smoke prevented the crew from making the required visual attack. After several attempts and with fuel running low, the aircraft proceeded to Nagasaki.
A break in the clouds allowed the crew to make a visual approach. Fat Man detonated over the city’s Urakami Valley, an industrial area containing major factories and military-related facilities. The surrounding hills limited the blast’s effects compared with what might have occurred over a flatter city center.
The bombing came three days after the destruction of Hiroshima by Little Boy. It also occurred on the same day that Soviet forces began their offensive against Japanese-held Manchuria. Together, these events intensified the crisis facing Japan’s leaders before the surrender announcement.