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. During Victoria's reign, he was 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.