On 26 December 1734 Charles married Princess Christine Wilhelmine of
Saxe-Eisenach (born: 1711), a daughter of
Duke John William III. The marriage produced four children: •
Charles William (1735–1803), Prince of Nassau-Usingen • Christine (1736–1741) •
Frederick Augustus (1738–1816), Prince of Nassau-Usingen (1803–1816) and Duke of Nassau (1806–1816) •
John Adolph (1740–1793), Prussian general In the second,
morganatic marriage, Charles married Magdalene Gross from Wiesbaden (born: 1712). From this marriage he also had four children: • Philippa Catherine von Biebrich (born: Idstein 17 May 1744; died: 17 July 1798), married at Biebrich June 1773 to Baron Karl Friedrich von Kruse (1738–1806) •
Karl Philipp von Biebrich, Count von Weilnau (born: 25 March 1746; died: 15 August 1789 Wiesbaden). The
Nassau Family Pact was executed in 1783, but he was not invited to be a signatory because of the morganatic marriage of his parents. • Sophie Christine (born: 20 June 1750; died: 16 November 1750) • Wilhelm Heinrich (born: 15 February 1755; died: 6 April 1755) ==Ancestry==