The Peace of Westphalia

The Thirty Years' War killed perhaps a third of the German-speaking population. Mercenary armies lived off the land they crossed, which is to say they ate it; entire regions reverted to forest, and contemporaries reported villages where the survivors had turned to cannibalism. By 1648, after thirty years and no decisive victory, every party — Catholic, Protestant, French, Spanish, Swedish, Habsburg — was financially exhausted and morally ashamed. The negotiations dragged on for five years in two cities at once, with diplomats shuttling between them. The treaties signed that October at Münster and Osnabrück tried to do something Europe had not seriously attempted: govern the relations between sovereign states without appealing to a higher religious authority.

The settlement is remembered, somewhat unfairly, as the founding of the modern state system — the Westphalian sovereignty that textbooks invoke. What it actually did was articulate a few load-bearing principles: that each prince determined the religion of his territory, now extending toleration to Calvinists alongside Lutherans and Catholics; that no outside power had standing to intervene on confessional grounds; that the boundaries of states were now boundaries of jurisdiction, not of faith. The mechanism mattered as much as the wording. Münster hosted the Catholic and imperial parties, Osnabrück the Protestants and Swedes, so that confessional enemies could negotiate without sharing a room; the result was the first genuinely multilateral congress, with scores of delegations bargaining as formal equals rather than supplicants to pope or emperor. It recognized the independence of the Dutch Republic and the Swiss, confirmed Sweden's and France's territorial gains, and granted the roughly three hundred German princes near-autonomy — the right to make alliances and wage war on their own account — hollowing out the Holy Roman Empire for two more centuries until Napoleon dissolved it in 1806. It was a deeply pragmatic exhaustion-peace, brokered not by clerics but by lawyers and career diplomats. But the abstract idea it crystallized — that there are territorial states, recognized as equals by other territorial states, each supreme inside its own borders — is the operating assumption of every multilateral institution from the UN Charter to the WTO, and the legal premise of the whole concept of non-interference.