The First World War saw the adoption in Britain of significant measures of constraint aimed at white working-class women and at black colonial, especially Indian, soldiers. While British and Dominion troops enjoyed considerable freedom of movement away from the battlefield, black men's and working-class women's mobility and their sexuality were closely controlled. In both instances, the most visible mark of disloyalty was the contraction or passing on of a sexually transmitted disease. Venereal disease control became one of the key justifications for wartime restrictions of these already disadvantaged groups. This article connects the discourse of imperial racism and its associated sexual anxieties to the ways in which such apparent disloyalties allowed authorities to deny citizenship claims from women and from colonial men through a reading of their sexuality.