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.
American military technology during World War II
On August 6 and 9, 1945, an atomic bomb was dropped on the Japanese cities of Hiroshima and Nagasaki instantly killing 120,000 people. Roughly 100,000 more people died of radiation poisoning in the following years. Six days after the dropping of the bomb on Nagasaki, the Japanese surrendered. The Manhattan Project was the leading collaborative scientific effort and the most secretive of the time. At first, several different labs had scientists working on smaller parts of the atom bomb, but they had no idea as to the magnitude of the project. Later, the project was moved to Los Alamos, New Mexico, led by renowned physicist J. Robert Oppenheimer.