For centuries, early modern scholars of the ius gentium (law of nations) were concerned with the body of norms that regulated alliances. And yet, when ‘modern international law’ emerged, in the early twentieth century, this topic had disappeared from the international legal lexicon. An early – and problematic – critic of this transition was Carl Schmitt (1888–1985), who shocked audiences with his The Concept of the Political (1932). By reading this monograph in tandem with the work of Francisco de Vitoria (1483–1546), I unearth the ways in which this early modern concern continues to reverberate in contemporary international legal thought. I do so, however, without losing sight of the challenges of reading these two authors today.
