Chapter 7 turns to Carl Schmitt’s seminal work The Nomos of the Earth (1950), which traces a history of international law by analyzing the transformations that took place in the system of states. Schmitt singled out three stages in this evolution. First came the medieval jus gentium of the respublica Christiana, in which the Pope and the Emperor formed a unity. This first stage waned with the rise of sovereign territorial states whose relations were governed by the jus publicum Europaeum. With this second phase, the medieval just war tradition gave way to a system marked by the centrality of sovereign states that recognized one another as just and equal enemies (justi et aequaes hostes). This notion of justus hostis made irrelevant what the reasons of war might be. What took hold, then, was a frame of thought predicated on a logic of law and statecraft that, no longer resting on a theological or moral foundation, took any sense out of the idea of criminalizing war. World War I plunged the jus publicum Europaeum into a crisis out of which came the refashioned meaning of war that went into the 1919 Treaty of Versailles, where a provision was introduced criminalizing wars of aggression.