Learning to cope with man’s mortality is central to the teachings of the world’s major religions. However, very little is known about the impact of life-and-death trauma on religiosity. This study exploits a natural experiment in military deployments to estimate the causal effect of traumatic shocks on religiosity. We find that combat assignment is associated with a substantial increase in the probability that a serviceman subsequently attends religious services regularly and engages in private prayer. Combat-induced increases in religiosity are largest for enlisted servicemen, those under age 25, and servicemen wounded in combat. The physical and psychological burdens of war, as well as the presence of military chaplains in combat zones, emerge as possible mechanisms.