Frederick William
Frederick William (German: Friedrich Wilhelm) (1620–1688), elector (ruler) of Brandenburg, 1640–88. He is often called the “Great Elector.” Frederick William rebuilt his country after the devastating Thirty Years' War (1618–48), drove the Swedes from Brandenburg, and secured from Poland the independence of Prussia—a part of his domain lying to the east of Brandenburg. He established a standing army and a navy and encouraged agriculture and trade. Under his son, Frederick I of Prussia, Brandenburg and Prussia became the Kingdom of Prussia.