William Frederick, Margrave of Brandenburg-Ansbach 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 and without legitimate issue. He married his first cousin, Christiane Charlotte of Württemberg-Winnental. He died
Caroline of Ansbach ruler of one of the smallest German states; he died of smallpox at the age of 32, when Caroline was three years old. Caroline and her only full sibling, her younger brother Margrave William Frederick, left Ansbach with their mother, who returned to her native Eisenach. In 1692, Caroline's widowed mother was pushed into an unhappy marriage with the Elector of Saxony, and she and her two children moved to the Saxon court at Dresden. Eleonore Erdmuthe was widowed again two years later, after her unfaithful husband contracted smallpox from his mistress. Eleonore remained in Saxony for another two years,