This innovative study offers the first-ever comparison of the military roles played by commissars, political officers, and chaplains in military settings ranging from the armies of Cromwell, the Jacobins, the Nazis, the Soviets, and the United States. Despite the stark differences in the political systems of the countries of these disparate armed forces, Dale R. Herspring argues that there are certain critical functions that must be fulfilled in every military, regardless of its ideological orientation. Most vital are motivation, morale boosting, and political socialization. In addition, Herspring's comparative historical analysis decisively demonstrates that the roles of commissars, political officers, and chaplains alike have evolved in ways that are crucial yet rarely understood either by policymakers or scholars.