For any society, participation in war invariably raises debates over the causes and consequences of involvement. Such debates often reveal preexisting divisions in society and tend to reflect larger social debates over national identity. When peace movements developed in the United States in response to a series of crises between 1898 and 1945, they raised important questions as to the nature of American society and values.

The Spanish-American War (1898) and the Philippines War (1898–1902)

The United States' decision to help Cuban insurgents overthrow their repressive Spanish colonial rulers in 1898 led to its acquisition of overseas territories for the first time. Although the majority of Americans supported these events, a vocal minority did not. In particular, when American soldiers became embroiled in a bitter fight against nationalists in the former Spanish colony of the Philippines, a peace movement emerged in opposition to America's newly discovered imperialist impulse. The...