Scholars of International Relations (IR) overwhelmingly accept that war became the exclusive legal prerogative of sovereign states after the Peace of Westphalia (1648). This legal arrangement has been a fundamental pillar of international stability ever since. The power of this historical narrative cannot be overstated. It has led scholars and policymakers to interpret the proliferation of non-state actors in contemporary conflicts as a threat to international order; it fortifies the argument that non-state entities should not have the right to wage war as it will unleash global chaos.

 But is this historical narrative accurate? Based on recent developments in the field of Historical IR, this project hypothesizes that for most of the period 1648-1914, one of the pillars of international order was in fact the distribution of the legal right to wage war to a wide array of actors. This only changed in the late 1800s, at the dawn of what many consider the bloodiest century in human history. This argument flips the classical narrative on its head: the monopoly of states on the right to wage war may in fact have had devastating consequences.

 Drawing on the turn towards the study of legal practices in the history of international law, I examine this preliminary argument by focusing on a crucial global legal practice: the making of peace treaties from 1648 to 1914. I construct a novel peace treaties dataset and determine when entities with less than full sovereignty lost the right to wage war.