Which 1648 peace settlement is commonly associated with the birth of the modern state-sovereignty system?

The Peace of Westphalia is the 1648 peace settlement commonly associated with the birth of the modern state-sovereignty system.

The settlement ended the Thirty Years' War in the Holy Roman Empire and the Eighty Years' War between Spain and the Dutch Republic. It consisted mainly of the treaties of Münster and Osnabrück, signed in October 1648. The agreements recognized the independence of the Dutch Republic and Switzerland and adjusted political and religious arrangements within the empire.

Later writers used “Westphalian sovereignty” to describe principles such as territorial authority and non-interference by outside powers. However, historians caution that the modern idea should not be projected too neatly onto 17th-century diplomacy. The Holy Roman Empire continued to contain many semi-autonomous territories, and sovereignty developed gradually through later practice.

The Peace of Augsburg of 1555 addressed an earlier phase of Catholic–Lutheran conflict. The Congress of Vienna, held in 1814–1815, reorganized Europe after the Napoleonic Wars rather than ending the Thirty Years' War.