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
Siege of Breda (1624) thereafter. The siege of 1624 captured the attention of European princes and, along with other battles like White Mountain (1620), played a part in the Spanish army regaining the formidable reputation it had held throughout the previous century. In the latter stages of the combined Eighty and Thirty Years' wars that had greatly strained Spanish resources, Breda was lost to the Dutch under Frederick Henry after a four-month siege. In the 1648 Treaty of Westphalia that ended the Thirty and Eighty Years' wars, it was ceded to the Dutch Republic. There were several motives for Spinola's siege of Breda. Because