Usually associated with the totalitarian regimes of the mid-twentieth century, concentration camps first appeared during the South African War (1899-1902). My project traces the development of the concentration camp in British imperial practice. By exploring the affinities between South African camps and earlier precursors, my project examines the evolving practices of encampment and the cultural mentalities that informed them. Metropolitan and colonial workhouses, military cantonments, arrangements for the control of infectious disease, and relief camps used to manage famine victims in late 19th-century South Asia provided an archive of imperial practice that informed the creation and management of camps in the South African War and beyond. In addition to tracing an evolving set of practices and policies, I argue that as a culturally embedded phenomenon, camps were the outcome of shifting mentalities of warfare, discipline, and the spatial organization of modern masses. Camps are now a ubiquitous feature of our contemporary geopolitical landscape. By locating the origins of the camp in liberal empire, I believe we can account for the continuing afterlife of the camp even after the demise of totalitarianism. My hypothesis is that British imperial agents were able to imprint the camp with a humanitarian pedigree that was mobilized to justify repressive measures throughout the twentieth century.