His Royal Highness Prince George Frederick Alexander Charles Ernest Augustus, KG, was born in Berlin. Originally styled Prince George of Cumberland, he spent his childhood in Berlin and in Britain. He lost the sight of one eye during a childhood illness, and the other in an accident in 1833. His uncle, King William IV, created him a Knight of the Garter on 15 August 1835. Upon the death of William IV and the ascension of Queen Victoria, the 104-year personal union of the British and Hanoverian thrones ended because of the operation of Salic Law in the German states. The Duke of Cumberland succeeded to the Hanoverian throne as King Ernst August I and Prince George of Cumberland became the Crown Prince of Hanover. As a legitimate male-line descendant of George III, he remained a member of the British Royal Family and was second in line to the British throne until the birth of Queen Victoria's first child, Victoria, Princess Royal, in 1841. Being totally blind there were doubts whether the Crown Prince was qualified to succeed to the government of Hanover; but his father decided that he should do so.
The Crown Prince succeeded his father as the King of Hanover and Duke of Brunswick-Lüneburg, as well as Duke of Cumberland and Teviotdale, and Earl of Armagh in the peerage of the United Kingdom on 18 November 1851, assuming the style George V. From his father and from his maternal uncle, Prince Charles Frederick of Mecklenburg-Strelitz (1785—1837), one of the most influential men at the Prussian court, George had learned to take a very high and autocratic view of royal authority. During his twenty-five year reign, he engaged in frequent disputes with the Hanoverian Landtag (parliament). Having supported Austria in the Diet of the German confederation in June 1866, he refused, contrary to the wishes of his parliament, to assent to the Prussian demand that Hanover should observe an unarmed neutrality during the Austro-Prussian War. As a result, the Prussian army occupied Hanover and the Hanoverian army surrendered on 29 June 1866 (The king and the Hanoverian royal family having fled to Austria). The Prussian government formally annexed Hanover on 20 September, but the deposed king never renounced his rights to the throne or acknowledged Prussia's actions. From exile in Gmunden, Austria, he appealed in vain for the European great powers to intervene on behalf of Hanover.
George married on 18 February 1843 at Hanover, Her Highness Princess (Alexandrine) Marie of Saxe-Altenberg (14 April 1818-9 January 1907), the eldest daughter of Josef, Duke of Saxe-Altenberg, by his wife Duchess Amelia of Württemburg. The marriage produced three children:
- Prince Ernst August of Hanover, 3rd Duke of Cumberland (21 September 1845-14 November 1923), Crown Prince of Hanover to 20 September 1866; succeeded his father as 3rd Duke of Cumberland and Teviotdale and Earl of Armagh on 12 June 1878; all British peerages suspended by Order-in-Council, 28 March 1919; succeeded his cousin, Duke Wilhelm of Brunswick-Wolfenbüttel (1806-1884) on 18 October 1884, but prevented from reigning by the Bundesrat (federal council of the German Empire), 1885; married Her Royal Highness Princess Tyra (29 September 1853-26 February 1933), the third daughter of King Christian IX of Denmark and Princess Lousie of Hesse-Cassel, and had issue.
- Princess Frederica of Hanover (9 January 1848-16 October 1926); married Litubert, Baron von Pawel-Rammingen (27 July 1843-20 November 1932); and had issue.
- Princess Marie of Hanover (3 December 1849-4 June 1904).
