George I of Greece

Born in Copenhagen on 24 December 1845, George seemed headed for the Royal Danish Navy when the Greek National Assembly deposed King Otto and elected him monarch at 17 - backed by Britain, France, and Russia. He married Grand Duchess Olga Constantinovna of Russia in 1867, founding a new Greek dynasty with ties threading through European royalty: his sisters Alexandra and Dagmar married into the British and Russian lines, making Edward VII and Alexander III his brothers-in-law, and linking him to five future kings. His 50 years on the throne - the longest in modern Greek history - brought territorial expansion: Britain ceded the Ionian Islands in 1864, Thessaly came after the Russo-Turkish War of 1877-1878, though the Greco-Turkish War of 1897 ended in defeat. During the First Balkan War, Greek forces captured much of Macedonia and Epirus. On 18 March 1913, George was assassinated in Thessaloniki, the city his troops had just won.