On August 6, 1945, 12 U.S. airmen climbed aboard a B-29 Superfortress bomber at an airfield on a tiny island in the middle of the Pacific Ocean. Their mission was so secret that even they were not certain of its true nature. The cargo was a special type of bomb, and their instruction was to head for the Japanese city of Hiroshima. By the end of the following day, the rest of the world would have heard about the bomb and about Hiroshima, and life would...