Peace of Westphalia - Wikipedia

On October 24, 1648, the Treaty of Westphalia ends The Thirty Year's War in the Holy Roman Empire. Switzerland's independence was also recognized. From the article:

"The Peace of Westphalia (German: Westfälischer Friede) was a series of peace treaties signed between May and October 1648 in the Westphalian cities of Osnabrück and Münster, largely ending the European wars of religion. The treaties of Westphalia brought to a close a calamitous period of European history which caused the deaths of approximately eight million people.[1] Scholars have identified Westphalia as the beginning of the modern international system, based on the concept of Westphalian sovereignty.

The negotiation process was lengthy and complex. Talks took place in two different cities, as each side wanted to meet on territory under its own control. A total of 109 delegations arrived to represent the belligerent states, but not all delegations were present at the same time. Three treaties were signed to end each of the overlapping wars: the Peace of Münster, the Treaty of Münster, and the Treaty of Osnabrück. These treaties ended the Thirty Years' War (1618–1648) in the Holy Roman Empire, with the Habsburgs and their Catholic allies on one side, battling the Protestant powers (Sweden, Denmark, Dutch, and Holy Roman principalities) allied with France (Catholic but anti-Habsburg). The treaties also ended the Eighty Years' War (1568–1648) between Spain and the Dutch Republic, with Spain formally recognising the independence of the Dutch.

The Peace of Westphalia established the precedent of peace established by diplomatic congress. A new system of political order arose in central Europe, based upon peaceful coexistence among sovereign states. Inter-state aggression was to be held in check by a balance of power, and a norm was established against interference in another state's domestic affairs. As European influence spread across the globe, these Westphalian principles, especially the concept of sovereign states, became central to international law and to the prevailing world order.[2]"