Historians, literary scholars, and international lawyers interested in the early modern period have all grappled with the problem of anachronism, yet mostly independently of one another. This essay uses the question of war crime in Shakespeare’s Henry V to argue that early modernists interested in international law need not reject synchronic historicism for explicitly anachronistic or presentist approaches. Proposing as a new context for Shakespeare’s play a little-known humanist disputation by the civil lawyer Alberico Gentili, De amis Romanis (1599), it illuminates a juridical approach to the international past cultivated in the early modern period alongside the rise of international law—an approach closely linked with literary epistemologies.