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
Treaty of Stettin (1653) Pomerania became Brandenburgian Pomerania. During the war, Sweden had occupied the Duchy of Pomerania in 1630. The last Griffin duke Bogislaw XIV died in 1637, his duchy was supposed to be inherited by Brandenburg, who based her claims on in the Treaty of Grimnitz. This however was hindered by the Swedish presence. The 1648 Peace of Westphalia ended the war, and Pomerania was to be partitioned between Brandenburg and Sweden. The 1650 Treaty of Nuremberg roughly defined the areas that should be under control of Sweden and Brandenburg, respectively. The precise border was drawn in the 1653 Treaty of Stettin,