Mediating Peace and Arbitration Mediation and arbitration have always been fundamental principles of peacebuilding and peacekeeping. Both mediation as part of the early modern ars tractandi and arbitration as a quasi-judicial method of conflict resolution were crucial to legal, political, and diplomatic practice in early modern times. Mediation and arbitration have in common the idea of involving an impartial third party to resolve conflicts between opposing sides to conclude a mutually satisfactory agreement. However, while the arbiter’s judgements were binding, the mediator had no power to enforce his decisions. Both were instruments of peacebuilding and as such they contributed decisively to the long-term establishment of norms and practices of peaceful conflict resolution.