Who married Ernest Augustus, King of Hanover?

Ernest Augustus (German: Ernst August; 5 June 1771 – 18 November 1851) was King of Hanover from 20 June 1837 until his death in 1851. As the fifth son of George III of the United Kingdom and Hanover, he initially seemed unlikely to become a monarch, but none of his older brothers had a legitimate son. When his brother William IV, who ruled both kingdoms, died in 1837, his niece Victoria inherited the British throne under British succession law, while Ernest succeeded in Hanover under Salic law, which barred women from the succession. This ended the personal union between Britain and Hanover that had begun in 1714. He remained heir presumptive to the British throne until the birth of his great-niece Victoria, Princess Royal, in 1840.

Ernest was born in London but was sent to Hanover in his adolescence for his education and military training. While serving with Hanoverian forces near Tournai against Revolutionary France, he received a disfiguring facial wound. He was created Duke of Cumberland and Teviotdale in 1799. Although his mother, Queen Charlotte, disapproved of his marriage in 1815 to her twice-widowed niece, Frederica of Mecklenburg-Strelitz, it proved happy. The eldest son of George III, the Prince of Wales (later George IV), had one child, Charlotte, who was expected to become the British queen, but she died in 1817, giving Ernest some prospect of succeeding to the British and Hanoverian thrones. However, his elder brother Prince Edward, Duke of Kent and Strathearn, fathered the eventual British heir, Victoria, in 1819 shortly before the birth of Ernest's only child, George.

Ernest was an active member of the House of Lords, where he maintained an extremely conservative record. There were persistent allegations (reportedly spread by his political foes) that he had murdered his valet, had fathered a son by his sister Sophia, and intended to take the British throne by murdering Victoria. Following the death of William IV, Ernest became Hanover's first resident ruler since George I. He had a generally successful fourteen-year reign but excited controversy near its start when he voided the liberal constitution granted before his reign and dismissed the Göttingen Seven, including the Brothers Grimm, from their professorial positions for protesting. In 1848, the King put down an attempted revolution. Hanover joined the German customs union in 1850 despite Ernest's reluctance. Ernest died the next year and was succeeded by his son, George V.

Frédérique Louise Caroline Sophie Charlotte Alexandrine de Mecklembourg-Strelitz (en allemand, Friederike von Mecklenburg-Strelitz), née le 3 mars 1778 à Hanovre, sous la période électorale de la ville (actuelle Allemagne) et décédée le 29 juin 1841 dans la même ville, au royaume de Hanovre, fille de Charles II de Mecklembourg-Strelitz et de Frédérique de Hesse-Darmstadt, est une princesse allemande de la maison de Mecklembourg.

Elle est élevée avec sa sœur Louise de Mecklembourg-Strelitz, future reine de Prusse, à Darmstadt, par sa grand-mère maternelle Marie-Louise de Leiningen-Dagsbourg-Falkenbourg, veuve du prince Georges-Guillaume de Hesse-Darmstadt, surnommée "princesse Georges".

Elle se marie en premières noces avec Louis-Charles de Prusse, frère cadet du futur roi de Prusse Frédéric-Guillaume III quelques semaines après le mariage de sa sœur aînée Louise avec le futur roi de Prusse.

Par ses trois mariages, Frédérique est successivement princesse de Prusse, princesse à Solms-Braunfels, et enfin duchesse de Cumberland et Teviotdale et reine de Hanovre.