In 1914 Europe descended into a slaughter unlike anything that had been seen before. Yet, far from seeing the conflict as a tragedy, many men welcomed it as a healthy development for society, a relief from peace. The Great Adventure explores the intellectual trends that made war seem a natural and high expression of social values. This is not a book about the specific causes of World War I, but a study of the mood in which it could take place.

What the book uncovers is a complex of deeply ingrained attitudes about manhood, sex, power, maturity, boredom, and war that defined a...