Sleeping-sickness control in southern Uganda created ideological openings for the articulation of colonial visions of African environments. Competing colonial agendas, Ugandans' positions in their own environments, and Ugandans' resistance and responses to colonial schemes determined how such visions played themselves out in practice. The emerging power of colonial science played an important role in colonial attempts at constructing nature and defining Africans' relationship with their environments through disease control. The combination of forced depopulations, strategic clearings, and planned resettlement in British sleeping-sickness control schemes in southern Uganda set in motion a cycle of long-term land alienation from 1906 to 1962 that reflected the particular relations between British science, environmental intervention, and colonisation.