Constantine I (, Konstantínos Αʹ, Vasiléfs ton Ellínon; – 11 January 1923) was King of Greece from 1913 to 1917 and from 1920 to 1922. He was commander-in-chief of the Hellenic Army during the unsuccessful Greco-Turkish War of 1897 and led the Greek forces during the successful Balkan Wars of 1912–1913, in which Greece won Thessaloniki and doubled in area and population. He succeeded to the throne of Greece on 18 March 1913, following his father's assassination.