Bockscar’s primary target during the August 9, 1945, atomic mission was Kokura.
The B-29 carried Fat Man and approached Kokura after departing Tinian. However, smoke and cloud obscured the aiming point. The crew made several attempts to find a clear visual path, but the target remained hidden. Because fuel was limited, the aircraft diverted to its secondary target, Nagasaki, where it released the bomb.
Kokura’s role created one of the best-known target mix-ups of the Pacific War. Nagasaki was not the mission’s first-choice city, although it had been selected as a secondary target. Smoke from a conventional raid on nearby Yahata, along with weather and the aircraft’s delayed arrival, contributed to the decision to divert. The phrase “Kokura’s luck” later became associated with the city’s escape from the atomic attack, though the mission’s outcome resulted from operational conditions rather than a single simple cause.