, 1754. On 8 May 1740, by proxy in London, and on 28 June 1740 in person in
Kassel, Frederick married
Princess Mary, fourth daughter of King
George II of Great Britain and
Caroline of Ansbach. They had four sons: • William (25 December 1741 – 1 July 1742) •
William I, Elector of Hesse (3 June 1743 – 27 February 1821) •
Charles (19 December 1744 – 17 August 1836), father of
Princess Louise Caroline of Hesse-Kassel and grandfather of
Christian IX of Denmark. •
Frederick (11 September 1747 – 20 May 1837), father of
Prince William of Hesse-Kassel and grandfather of
Queen Louise of Denmark. In December 1745, Frederick landed in
Scotland with 6000 Hessian troops to support his father-in-law, George II of Great Britain, in dealing with the
Jacobite rising. Although he supported the
"Protestant succession" in Great Britain on this occasion, Frederick later converted from
Calvinism to
Catholicism. In February 1749, Frederick and his father visited the Archbishop-Elector of Cologne,
Clemens August of Bavaria, who received Frederick into the
Catholic Church. Despite his exertions in support of her father, Frederick's marriage with the British princess was not a happy one. The couple were living apart from each other by 1747, and were formally separated in 1755. Mary moved to Denmark the following year to care for the children of her late sister
Louise of Great Britain, who had died in 1751. All three of the couple's surviving sons moved with Mary to Denmark. Two of them, including Frederick's heir William, later married Danish princesses, their first cousins. The younger sons lived permanently in Denmark, rising to high office in the court of their cousin; only William returned to Germany upon inheriting the
principality of Hanau. He also later succeeded Frederick as Landgrave of Hesse-Kassel. Mary died in 1772, and Frederick lost little time in marrying again. On 10 January 1773, at Berlin, he married
Margravine Philippine, daughter of
Frederick William, Margrave of Brandenburg-Schwedt and
Sophia Dorothea of Prussia. No children were born of this marriage. ==Ruler==