To a generation of soldiers coping with their experiences in the Vietnam War, the affliction is called posttraumatic stress disorder. To the generation that fought Hitler it was combat fatigue, and to their fathers who had served on the Western Front, shell shock. Whatever the name, the roots of PTSD go back well beyond the American Civil War, and in a powerful essay, the military historian Roger J. Spiller seeks out the historical antecedents of one of the bleakest legacies of our effort in Southeast Asia.