This paper begins to answer these questions by looking at Sir Reginald Coupland (1884–1952), the prolific colonial historian, author and policy advisor, who was involved in all three major partitions that changed the contours of the British Empire during the first half of the twentieth century. Setting Copland against the backdrop of imperial federalist thought originating in the late Victorian era and revived in Edwardian era and following WWI, this paper argues that, paradoxically, these partitions were designed as mechanisms of imperial containment, not nationalist secession, and that despite its top-down image, partitions in fact were often based on an intimate dialogue between policy makers from the imperial metropole and the actors on the colonial periphery. Moreover, this reconstruction also reveals partition less as a single idea and more as a “package deal,” or a set of interrelated theories that included new notions of ethnic “un-mixing,” population exchange, and statehood-within-Commonwealth. Such a reconceptualization underscores the historical specificity of the three partitions of Ireland, India and Palestine, and permits us to re-evaluate their enduring legacies.