At 2:45 in the morning of August 6, 1945, an American B-29 bomber flew north from Tinian Island in the Marianas toward Japan. Three and a half hours later, over the city of Hiroshima, the Enola Gay dropped an 8,900-pound atomic weapon from its specially modified bomb bay. Two thousand feet above the ground, the bomb, dubbed „Little Boy“ by its makers, detonated, leveling almost 90% of the city.

On August 9, another B-29, Bockscar, set out for the Kokura Arsenal on the southwest Japanese island of Kyushu. Foul weather, however, persuaded the pilot to proceed instead toward Nagasaki, the home of a Mitsubishi torpedo factory.