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
Eighty Years' War Roman Empire of 14 and 24 October 1648, which comprise the Peace of Westphalia, but which were not signed by the Republic, the Republic now also gained formal "independence" from the Holy Roman Empire, just like the Swiss Cantons. In both cases this was just a formalisation of a situation that had already existed for a long time. France and Spain did not conclude a treaty and so remained at war until the peace of the Pyrenees of 1659. The peace was celebrated in the Republic with sumptuous festivities. It was solemnly promulgated on the 80th anniversary of the execution