The American military tradition rests on several pillars, some explicitly articulated, others substantially less so. Among the most significant yet elusive of these pillars is the principle of citizen service. Stripped to its core, the principle of citizen service is built on a single idea: the military service obligations of citizenship. Military service is a responsibility incurred solely because of one's membership in the political community of citizens; and precisely because of this duty, the state may legitimately compel military service from its citizens. Depending upon whether it is viewed from the perspective of the state or the citizen, then, compulsion and obligation form two sides of the same relationship. It is this particular relationship between citizen and state--one of the obligation to serve, and of the corresponding power to compel service--that defines citizen service. 
As a principle, citizen service is polymorphous. It may be embodied in a range of discrete military institutions, most notably for the U.S. in the compulsory militia as well as the conscript army. The principle of citizen service animates and regulates both of these institutions, providing each with a rationale and a guide for action, yet without compromising their distinctiveness. Within any particular conscript army or compulsory militia, however, there are a number of ways in which the principle of citizen service may be put into practice on the ground, and an even larger array of procedures that may be used to make citizen service a social and organizational reality. The principle alone does not dictate how any particular military institution exacts compulsory service, or even whether that institution actually compels citizens to serve.
Citizen service in the United States has proven elusive for many reasons, not the least of which is the temptation to treat it in abstractions alone, focusing primarily on the logic of the principle and the way it may be seen in different institutional formats. If we are to render it any less elusive, however, it is by moving beyond abstractions to offer an analysis of citizen service as a historical and institutional reality. One of the most promising avenues for research lies in examining precisely how concrete sets of institutional arrangements embody the principle of citizen service and realize it on the ground at specifiable historical junctures. By examining how actual institutional arrangements breathe life into the principle, we are able to capture much of the richness and complexity of American citizen service.
Historical and institutional treatments of citizen service in the United States have proliferated in the last two decades, most recently in the work of David R. Segal, James Burk, and Eliot Cohen.  Tacit in the first, and increasingly explicit in the latter pair, is the sense that two fundamentally different perspectives on citizen service coexist in American history. According to the first, exemplified by the work of John Whiteclay Chambers II, citizen service in America is identified with the introduction of large-scale conscription during World War I.  On this formulation, citizen service reached its...