Fred Halliday saw revolution and war as the dual motors of modern international order. However, while war occupies a prominent place in International Relations (IR), revolutions inhabit a more residual location. For Halliday, this is out of keeping with their impact - in particular, revolutions offer a systemic challenge to existing patterns of international order in their capacity to generate alternative orders founded on novel forms of political rule, economic organization and symbolic authority. In this way, dynamics of revolution and counter-revolution are closely associated with processes of international conflict, intervention and war. It may be that one of the reasons for Halliday's failure to make apparent the importance of revolutions to IR audiences was that, for all his empirical illustrations of how revolutions affected the international realm, he did not formulate a coherent theoretical schema which spoke systematically to the discipline. This article assesses Halliday's contribution to the study of revolutions, and sets out an approach which both recognizes and extends his work. By formulating ideal-typical 'anatomies of revolution', it is possible to generate insights that clarify the ways in which revolutions shape international order.