Charles, Prince of Nassau-Usingen

Charles was born in Usingen, the son of William Henry of Nassau-Usingen and Countess Charlotte Amalia of Nassau-Dillenburg.

His father died in 1718, when he was still a minor. His mother acted as regent for Charles and his younger brother William Henry II. In 1728, he inherited the counties of Nassau-Ottweiler, Nassau-Idstein and Nassau-Saarbrücken from his second cousin Frederick Louis. These counties were then added to his county of Nassau-Usingen.

In 1734, he was declared an adult by Emperor Charles VI. In 1735, he and William Henry II divided their inheritance. Charles received Usingen, Idstein, Wiesbaden and Lahr; William Henry II received Nassau-Saarbrücken and some smaller territories. He then moved his residence from Usingen in the Taunus to Schloss Biebrich in Biebrich and continued the progressive policies of his mother.

Charles died in 1775 in Biebrich and was succeeded by his son Charles William.

On 26 December 1734 Charles married Duchess 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)

• Ernst Joachim (1882), "Karl von Nassau-Usingen", Allgemeine Deutsche Biographie (ADB) (in German), 15, Leipzig: Duncker & Humblot, p. 313