King Alexander assumes the throne of Greece after his father, Constantine I, abdicates under pressure from allied armies occupying Athens.

The Triple Entente (from French entente [tt] meaning "friendship, understanding, agreement") 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 Paris and London, and the Anglo-Russian Entente of 1907. It formed a powerful counterweight to the Triple Alliance of Germany, Austria-Hungary, and Italy. The Triple Entente, unlike the Triple Alliance or the Franco-Russian Alliance itself, was not an alliance of mutual defence.

The Franco-Japanese Treaty of 1907 was a key part of building a coalition as France took the lead in creating alliances with Japan, Russia, and (informally) with Britain. Japan wanted to raise a loan in Paris, so France made the loan contingent on a Russo-Japanese agreement and a Japanese guarantee for France's strategically vulnerable possessions in Indochina. Britain encouraged the Russo-Japanese rapprochement. Thus was built the Triple Entente coalition that fought World War I.At the start of World War I in 1914, all three Triple Entente members entered it as Allied Powers against the Central Powers: Germany and Austria-Hungary. On September 4, 1914, the Triple Entente issued a declaration undertaking not to conclude a separate peace and only to demand terms of peace agreed between the three parties. Historians continue to debate the importance of the alliance system as one of the causes of World War I.

Alexander (Greek: Αλέξανδρος, Aléxandros; 1 August 1893 – 25 October 1920) was King of Greece from 11 June 1917 until his death three years later, at the age of 27, from the effects of a monkey bite.

The second son of King Constantine I, Alexander was born in the summer palace of Tatoi on the outskirts of Athens. He succeeded his father in 1917, during World War I, after the Entente Powers and the followers of Eleftherios Venizelos pushed Constantine I, and his eldest son Crown Prince George, into exile. Having no real political experience, the new king was stripped of his powers by the Venizelists and effectively imprisoned in his own palace. Venizelos, as prime minister, was the effective ruler with the support of the Entente. Though reduced to the status of a puppet king, Alexander supported Greek troops during their war against the Ottoman Empire and Bulgaria. Under his reign, the territorial extent of Greece considerably increased, following the victory of the Entente and their Allies in the First World War and the early stages of the Greco-Turkish War of 1919–1922.

Alexander controversially married the commoner Aspasia Manos in 1919, provoking a major scandal that forced the couple to leave Greece for several months. Soon after returning to Greece with his wife, Alexander was bitten by a domestic Barbary macaque and died of sepsis. The sudden death of the sovereign led to questions over the monarchy's survival and contributed to the fall of the Venizelist regime. After a general election and a referendum, Constantine I was restored to the throne.