E.H. Carr’s The Twenty Years’ Crisis (1939), has a well-deserved reputation as a classic text that helped launch the academic discipline of International Relations (IR). Not only did Carr identify and dissect what would emerge as the two leading schools of thought in IR—utopianism and realism—he also applied a keen eye to the tumultuous decades after the Great War, when efforts to re-establish a functioning international political system foundered on a fundamental disruption to its most important operating principles. Carr framed these in terms of the relationship between power and morality, arguing that the latter had ultimately to accommodate itself to the changing dynamics of the former. Subsequent IR scholarship has mostly located Carr in the realist tradition of the discipline, concerned primarily with the balance of power and pursuit of national interest.1