Amid the European alliances of 1914, Greece found itself in a quandary. It had a number of reasons for opposing the Central Powers. First, the unredeemed Greeks of the East were cause for opposing any alliance that included the Porte. Second, Bulgaria, still a rival for territory in Macedonia, had aligned itself with the Central Powers. Third, treaty obligations bound Greece to Serbia, which was in a territorial dispute with the AustroHungarian Empire over Bosnia. Finally, the Entente powers had earned Greek loyalty by supporting Greek national aspirations since the struggle for independence. On the other hand, Queen Sofia of Greece was the sister of Kaiser Wilhelm of Germany, and the German military establishment had considerable influence among Greek military leaders, many of whom had been trained in Germany. When World War I erupted in the summer of 1914, these interests came into direct conflict, and Greece was compelled to choose a side.

King Constantine, whose sympathies were clearly with the Central Powers, believed that Greece's interests could best be served by maintaining neutrality. Prime Minister Venizelos, on the other hand, was staunchly pro-Entente. His position was reinforced in January 1915 when Britain promised to award Asia Minor (including all of modern Turkey) to Greece if Greece would lend military support to the Serbs and to the proposed British and French invasion of the Turkish mainland at Gallipoli (Geliboli). Venizelos, believing that the Entente would win the war and make good on its offer, resigned as prime minister when Constantine and the Greek general staff opposed alliance with the Entente. The dispute over national policy finally brought a constitutional crisis that came to be called the Ethnikos Dikhasmos, or the National Schism.