In the early modern age, the settlement of disputes between the actors of ‘international’ relations hinged on communication channels and negotiation networks that were meant to limit the recourse to violence. Multireligious Renaissance Europe saw the emergence of the jus gentium – as a distinct, gestating branch of law – and modern diplomacy, perceived as a social and cultural practice used not only by sovereigns, but also by non-sovereign actors – a practice allowing both Europeans and non-Europeans to engage in formal and informal interactions, in state and non-state settings, through the elaboration of common languages, of (verbal and symbolic) communication practices and of shared political and legal cultures. In a belligerent era, which spawned many wars, European diplomacy developed new forms of negotiation that attest to an elaborate ‘art of peace’. By the end of the period, the Thirty Years War ended with the first experience of dispute settlement through multilateral talks involving nearly all European powers in Westphalia (1643-9) and reflecting conflicts that attest to the successive integration of non-European territories in ongoing European dispute. The congress demonstrated both the effectiveness and the limitations of this innovative negotiation model.