Charles Sweeney
Poor bombing visibility and an increasingly critical fuel shortage eventually forced "Bockscar" to divert from Kokura and attack the secondary target, Nagasaki. As they approached Nagasaki, the heart of the city's downtown was covered by dense cloud, and Sweeney and the plane's weaponeer, Commander Ashworth, initially decided to bomb Nagasaki using radar. However, a small opening in the clouds allowed "Bockscar's" bombardier to verify the target as Nagasaki. As the crew had been ordered to drop the bomb visually if possible, Sweeney decided to proceed with a visual bomb run. "Bockscar" then dropped "Fat Man", with a blast yield equivalent to 21 kilotons of TNT. It exploded 43 seconds later at above the ground, at least northwest of the planned aim point. The failure to drop "Fat Man" at the precise bomb aim point caused the atomic blast to be confined to the Urakami Valley. As a consequence, a major portion of the city was protected by the intervening hills, and only 60% of Nagasaki was destroyed. The bombing also severed the Mitsubishi arms production extensively and killed an estimated 35,000-40,000 people outright, including 23,200-28,200 Japanese industrial workers, 2,000 Korean slave laborers, and 150 Japanese soldiers.
Nagasaki
Less than a second after the detonation, the north of the city was destroyed and 35,000 people were killed. Among the deaths were 6,200 out of the 7,500 employees of the Mitsubishi Munitions plant, and 24,000 others (including 2,000 Koreans) who worked in other war plants and factories in the city, as well as 150 Japanese soldiers. The industrial damage in Nagasaki was high, leaving 68–80% of the non-dock industrial production destroyed. It was the second and, to date, the last use of a nuclear weapon in combat, and also the second detonation of a plutonium bomb. The first combat use of a nuclear weapon was the "Little Boy" bomb, which was dropped on the Japanese city of Hiroshima on August 6, 1945. The first plutonium bomb was tested in central New Mexico, United States, on July 16, 1945. The Fat Man bomb was somewhat more powerful than the one dropped over Hiroshima, but because of Nagasaki's more uneven terrain, there was less damage.