Westphalia to be Catholic. Osnabrück was divided almost equally between Catholicism and Protestantism. Parts of Westphalia came under Brandenburg-Prussian control during the 17th and 18th centuries, but most of it remained divided by duchies and other areas of feudal power. The Peace of Westphalia of 1648, signed in Münster and Osnabrück, ended the Thirty Years' War. The concept of nation-state sovereignty resulting from the treaty became known as "Westphalian sovereignty". After the defeat of the Prussian Army by the French at the Battle of Jena–Auerstedt, the Treaty of Tilsit in 1807 made the easternmost portion of today's Westphalia part of the
Peace of Münster for approval; it was ratified by the Spanish and Dutch delegations on 15 May, with the States General narrowly approving the Treaty on 5 June 1648. The Peace of Münster together with the Treaty of Münster between the Holy Roman Emperor, France and their allies and the Treaty of Osnabrück involving the Holy Roman Empire, Sweden and their allies were collectively known as the Peace of Westphalia. While European conflict continued, this marks a significant point in the transition to sovereignty based on states rather than individuals e.g. the Hapsburgs. Sovereignty has been defined by historian Harry Hinsley as "the