William Frederick, Margrave of Brandenburg-Ansbach in Unterreichenbach and was succeeded by his son Charles William Frederick, called "The Wild Margrave". William Frederick, Margrave of Brandenburg-Ansbach William Frederick, Margrave of Brandenburg-Ansbach (8 January 1686 – 7 January 1723), was Margrave of the Principality of Brandenburg-Ansbach from 1703 until his death in 1723. He was the younger brother of Caroline of Ansbach and thus brother-in-law of George II of Great Britain. William Frederick was born in Ansbach in 1686 to John Frederick, Margrave of Brandenburg-Ansbach, and his second wife, Eleonore Erdmuthe of Saxe-Eisenach. His two surviving half-brothers, Margraves Christian Albert and George Frederick II, both died unmarried
Caroline of Ansbach until her death in 1696. The orphaned Caroline and William Frederick returned to Ansbach to stay with their elder half-brother, Margrave George Frederick II. George Frederick was a youth with little interest in parenting a girl, and so Caroline soon moved to Lützenburg outside Berlin, where she entered into the care of her new guardians, Frederick, Elector of Brandenburg, and his wife, Sophia Charlotte, who had been a friend of Eleonore Erdmuthe. Frederick and Sophia Charlotte became king and queen of Prussia in 1701. The queen was the daughter of Dowager Electress Sophia of Hanover, and the sister of George,