When is a war a holy crusade? And when does theology cause Christians to condemn violence? In American Crusade, Benjamin Wetzel argues that the Civil War, the Spanish-American War, and World War I shared a cultural meaning for white Protestant ministers in the United States, who considered each conflict to be a modern-day crusade.

American Crusade examines the "holy war" mentality prevalent between 1860 and 1920, juxtaposing mainline Protestant support for these wars with more hesitant religious voices: Catholics, German-speaking Lutherans, and African American Methodists. The specific theologies and social locations of these more marginal denominations made their ministries highly critical of the crusading mentality. Religious understandings of the nation, both in support of and opposed to armed conflict, played a major role in such ideological contestation. Wetzel's book questions traditional periodizations and suggests that these three wars should be understood as a unit. Grappling with the views of America's religious leaders, supplemented by those of ordinary people, American Crusade provides a fresh way of understanding the three major American wars of the late nineteenth and early twentieth centuries.