 Wilhelmine Carolina was a daughter of William IV, Prince of Orange and Anne, Princess Royal and Princess of Orange.Anne was in turn the eldest daughter of George II of Great Britain and Caroline of Ansbach.On 31 July 1788 in Hachenburg, Frederick William married Burgravine Louise Isabelle of Kirchberg (Hachenburg, 19 April 1772 - Vienna, 6 January 1827).