Among the quips of Winston Churchill, his lapidary sentence “[i]f Hitler invaded Hell, I would make at least one favourable reference to the Devil in the House of Commons” surely deserves a high rank. It reminds us of the importance of juridical discourses and practices of alliance —often motivated by animosity towards a third party rather than inherent friendship between polities— in the global history of international law. Yet, in the contemporary literature of this field, one finds little reference to the theory and history of alliance-making —or breaking, for that matter. One can contrast this with an older tradition of literature (for instance, what we now understand as the 18th century “Law of Nations”, or 19th “classical international law”) which was critically concerned with the law and practice of inter-polity alliance. In this project, I interrogate how the categories of alliance were exorcised from international legal scholarship precisely during the same period in which coalitions, confederations, and military associations increasingly gained a salient role in the creation and maintenance of international order. By rewriting the law of alliances back into the history of the discipline, I trace some of the (dis)continuities that have haunted the quest for international organization.