King Constantine I

Constantine I was King of Greece from 18 March 1913 to 11 June 1917 and again from 19 December 1920 to 27 September 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 expanded to include Thessaloniki, doubling in area and population. The eldest son of George I of Greece, he succeeded to the throne following his father's assassination in 1913.

Constantine's disagreement with Prime Minister Eleftherios Venizelos over whether Greece should enter World War I led to the National Schism. Under Allied duress, the country was essentially split between the pro-Venizelos North and the royalist South, ushering in a protracted civil war.