British Royal Navy officer and the elder son of Louis Mountbatten, 1st Marquess of Milford Haven (Prince Louis of Battenberg), and Princess Victoria of Hesse and by Rhine. He was born Prince George of Battenberg and styled Earl of Medina between 1917 and 1921.
His siblings were Princess Alice (mother of Prince Philip, Duke of Edinburgh, to whom he was a mentor in Philip’s adolescence), Queen Louise of Sweden and Louis Mountbatten, 1st Earl Mountbatten of Burma (who assumed the role of Philip’s mentor after George’s death).
George followed his father into the Royal Navy, and after passing out from the Royal Naval College at Dartmouth, was promoted to sub-lieutenant on 15 January 1913. He was promoted to lieutenant on 15 February 1914, and served in the First World War.
In 1917, his father and several of his relations relinquished their German names, styles and titles in exchange for British peerages at the behest of George V. Accordingly, Prince George dropped the style of Serene Highness and his surname was anglicised to “Mountbatten.” When his father was created Marquess of Milford Haven in late 1917, George received the courtesy title of Earl of Medina, succeeding to his father’s peerage after his death in September 1921.
Lord Milford Haven, as George was now, remained in the Royal Navy after the war; he was promoted to lieutenant-commander on 15 February 1922 and to commander on 31 December 1926. In 1932, he retired from active service at his own request, with effect from 9 December of that year. On 6 November 1937, shortly before his death, he was promoted to the rank of captain on the retired list.
An accomplished mathematician, the Marquess “could work out complicated gunnery problems in his head” and “read books on calculus casually on trains”. Queen Elizabeth II, his niece-in-law, considered him “one of the most intelligent and brilliant of people”.
Prince George of Battenberg, as he then was, married Countess Nadejda Mikhailovna de Torby (daughter of Russian Grand Duke Michael Mikhailovich Romanov and his morganatic wife, Countess Sophie von Merenberg) on 15 November 1916 at the Russian Embassy, Welbeck Street, London. They had two children.
Lord Milford Haven died on 8 April 1938 of bone marrow cancer, aged 45, in London.
Link to Wikipedia biography