The youngest of Dorothea's sons was Margrave Christian Ludwig (1677–1734), officer and administrator of Halberstadt, the honoree of Bach's "Brandenburg Concertos". The brisk building activity was continued by Philipp William's son and successor, Margrave Frederick William (1700-1771). Initially under the tutelage of his uncle Frederick (Prussian king as "Frederick I" since 1701) he ruled his dominions from 1731 onwards and began to develop Schwedt into a country seat for the cadet line. In 1734 he had married his cousin Princess Sophia Dorothea of Prussia, a sister of King Frederick the Great. As he left no male heirs upon his death, Philip William's youngest son, Frederick Henry (1709-1788) ruled as the last Margrave of Brandenburg-Schwedt and developed Schwedt into a cultural center. Known for his numerous love affairs, his marriage with Princess Leopoldine Marie of Anhalt-Dessau likewise produced no male descendants. After Frederick Henry's death in 1788, the male line of Brandenburg-Schwedt became extinct and their appanage territories reverted to the King of Prussia. For a few years, beginning in 1794, the castle of Schwedt was the residence of King Frederick William II of Prussia's second son, Prince Frederick Louis Charles of Prussia. The last Schwedt heiress Elisabeth Louise, daughter of Margrave Frederick William, died in 1820. Descendants from Sophia Dorothea of Schleswig-Holstein-Sonderburg-Glücksburg (1636–1689) by her marriage with Frederick William, Elector of Brandenburg: