King Alexander assumes the throne of Greece after his father, Constantine I, is deemed to have abdicated under pressure from allied armies occupying Athens.

Alexander was King of Greece from 11 June 1917 until his death on 25 October 1920.

The Kingdom of Greece was the Greek nation-state established in 1832 and was the successor state to the First Hellenic Republic. It was internationally recognised by the Treaty of Constantinople, where Greece also secured its full independence from the Ottoman Empire after nearly four centuries. It remained a Kingdom until 1924, when the Second Hellenic Republic was proclaimed, and from the Republic's collapse in 1935 to its dissolution by the Regime of the Colonels in 1973. A referendum following the regime's collapse in 1974 confirmed the effective dissolution of the monarchy and the creation of the Third Hellenic Republic. For much of its existence, the Kingdom's main ideological goal was the Megali Idea, which sought to annex lands with predominately Greek populations.

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.

The Triple Entente describes the informal understanding between the Russian Empire, the French Third Republic, and the United Kingdom of Great Britain and Ireland. It was built upon the Franco-Russian Alliance of 1894, the Entente Cordiale of 1904 between France and Britain, and the Anglo-Russian Entente of 1907. It formed a powerful counterweight to the Triple Alliance of the German Empire, the Austro-Hungarian Empire, and the Kingdom of Italy. The Triple Entente, unlike the Triple Alliance or the Franco-Russian Alliance itself, was not an alliance of mutual defence.