Conscience and the freedom to exercise conscience have long been cherished civil liberties in western democracies. However, during World War I, traditional concepts of conscience and conscientious objection to military service were challenged by the demands of conscription and militarism in the United States and Britain. This dissertation examines the definition, context, and exercise of conscience by conscientious objectors (COs) during the war. This study finds that conscience existed in a dynamic state. COs were compelled by changing circumstances to reevaluate and restate their objections as they responded to changing circumstances in army camps, guardhouses, and prisons.

To understand how COs' consciences were exercised and subsequently expanded, this study begins with an examination of the definition and evolution of conscience in the philosophical and religious traditions in western civilization. Next, a brief history of conscription in the United States and Britain provides the context in which COs acted. This dissertation also scrutinizes ways in which COs' expression of conscience clashed with societal notions of masculinity and citizenship. Finally, the role of military psychologists tasked with establishing the "sincerity" of COs' consciences in order to categorize the men for administrative processing is also examined.

COs in this study are divided into two distinct groups, religious and political objectors, with special attention paid to "absolutist" objectors who refused to participate in any way in their nation's military system. This dissertation utilizes information from first-person accounts, including diaries, letters, and unpublished manuscripts as well as court-martial records, newspaper clippings and government documents.