Why has nobody written this book before? “Coward” remains one of the English language’s harshest epithets, but its meaning has become less clear. The term was once reserved for those who turned away from physical danger. But the more that societies come to appreciate the fact of human frailty, the less cowardice appears as a moral failing and the less censorious people become of behavior that not long ago would have led, in a military context, to a court-martial and even execution. At the same time, societies have become less tolerant of a different kind of cowardice: silence in the face of egregious wrongdoing. In this elegant and thoughtful discussion that draws on literature and films as well as military case law, Walsh thoroughly explores how the concept of cowardice has evolved as a result of changes in the way societies understand morality, human nature, and the nature of war. In the end, he argues, societies need a firm concept of cowardice; without it, they cannot grasp what it means to act courageously.