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 Stettin (1630) Pomerania to enforce Brandenburg's claims on succession, but they were defeated by Sweden in the ensuing battles. Some of the Pomeranian nobility had changed sides and supported Brandenburg. By the end of the war, the treaty was superseded by the Peace of Westphalia (1648) and the subsequent Treaty of Stettin (1653), when Pomerania was partitioned into a western, Swedish part (Western Pomerania, thenceforth Swedish Pomerania), and an eastern, Brandenburgian part (Farther Pomerania, thenceforth the Brandenburg-Prussian Province of Pomerania). Following the Capitulation of Franzburg in 1627, the Duchy of Pomerania was occupied by forces of Ferdinand II, Holy Roman Emperor, under