[dropcap]C[/dropcap]apt. Kermit K. Beahan of Houston tossed and turned the night of Aug. 8, 1945 knowing that the next day, which also happened to be his twenty-seventh birthday, he might be called upon to drop the second atom bomb on Japan.

The bloody 11-week battle for Okinawa, that ended in June 1945 with 49,000 Allied casualties, showed defeat had not diminished the fanatical determination of the Japanese to fight to the death. For “Operation Olympic,” the invasion of the home isl...