Margraviate of Brandenburg fief of the Polish–Lithuanian Commonwealth, to which the electors paid homage. The electors of Brandenburg spent the next two centuries attempting to gain lands to unite their separate territories (the Mark Brandenburg, the territories in the Rhineland and Westphalia, and Ducal Prussia) to form one geographically contiguous domain. In the Peace of Westphalia ending the Thirty Years' War in 1648, Brandenburg-Prussia acquired Farther Pomerania and made it the Province of Pomerania by the Treaty of Stettin (1653). In the second half of the 17th century, Frederick William, the "Great Elector", developed Brandenburg-Prussia into a major power. The state constructed Brandenburg's
Treaty of Grimnitz Sweden refused to hand over the duchy. An agreement was reached to partition the duchy into a Swedish and a Brandenburgian part in the Peace of Westphalia (1648), which was put into effect in the Treaty of Stettin (1653). Treaty of Grimnitz The Treaty of Grimnitz (26 August 1529) was the final settlement of a long-standing dispute between the House of Pomerania and the House of Hohenzollern regarding the legal status and succession in the Duchy of Pomerania. It renewed and amended the Treaty of Pyritz of 1493. With some formal caveats, the House of Pomerania received the Duchy of