The mission of the United States Navy expanded significantly because of the presence of the institution of racial slavery on American soil. Most important, both proslavery and antislavery forces favored, for very different reasons, a substantial naval buildup in the late 1850s. The navy had, however, long been engaged in securing the nation’s borders against slave smuggling, an activity that also seemed to have broad support at the time. Finally, somewhat more controversially, the navy had been associated with the American Colonization Society’s Liberian enterprise from its very inception, deciding to deploy vessels to Africa in an otherwise unimaginable time frame. The relationship between the presence of slavery and the pre–Civil War activities of the navy is a largely untold—or, at best, half-told—story of American state development.