In the Global North, mass warfare created a huge demand for social protection, pushing governments to provide income for invalids, war victims, and the survivors of fallen soldiers. Most European colonial powers, including France and Great Britain, recruited soldiers and other security forces not only from their metropoles but also from their colonies during both World Wars. However, the question of how mass warfare influenced social reforms in former colonies has not been systematically addressed, particularly with respect to how these influences varied across colonial powers. To begin to address this gap, this paper explores the warfare–welfare nexus in the context of British and French colonies of West Africa around World War I (WWI). The paper finds that, while Britain and France had similar overarching imperial and military objectives in West Africa of securing their colonies, enforcing order within them, and promoting commerce to increase profit, they went about achieving them very differently, with direct and indirect implications for social reforms after WWI. While only a first step, research on the distinct nature of the warfare–welfare nexus in colonial contexts is critical in order to historicize and close research gaps by widening and deepening our understanding of social policy trajectories in countries of the Global South.