Seventy-five years ago, the United States waged the only nuclear war in history. Among the truths held self-evident by millions of Americans is the notion that the atomic destruction of Hiroshima and Nagasaki saved lives, both American and Japanese. The choice, Americans are told starting as school children and throughout their lives by largely uncritical media, was between nuclear war and an even bloodier protracted invasion of Japan, whose fanatical people would have fought to the death defending their homeland and their divine emperor. As with so many other dark chapters in US history, the official narrative of the decision to unleash the most destructive weapon humanity has ever known upon an utterly defeated people is deeply flawed. The Japanese had in fact been trying to find a way to surrender with honor for months before the atomic bombs were dropped, and US leaders knew...