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
Dominions of Sweden Norway to the king of Sweden under the Treaty of Kiel, which followed on Second War against Napoleon. However the treaty of Kiel never came into force: instead sovereignty of Western Pomerania passed to Kingdom of Prussia, who already held the eastern parts and merged them into the Province of Pomerania. Norway declared her independence, but was forced after a short war into a personal Union with Sweden. Sweden received the German town of Wismar with the surrounding countryside in the Peace of Westphalia (1648). In 1803 Wismar was pawned, in exchange for a loan, and control was handed over