Greece entered World War II on 28 October 1940, when the Italian army invaded from Albania, beginning the Greco-Italian War. The Greek army was able to stop the invasion and even push back the Italians into Albania, thereby winning one of the first victories for the Allies. The Greek successes and the inability of the Italians to reverse the situation forced Nazi Germany to intervene in order to protect her main Axis partner’s prestige. The Germans invaded Greece and Yugoslavia on 6 April 1941, and overran both countries within a month, despite British aid to Greece in the form of an expeditionary corps. The conquest of Greece was completed in May with the capture of Crete from the air, although the Fallschirmjäger suffered such extensive casualties in this operation that the Germans abandoned large-scale airborne operations for the remainder of the war. The German diversion of resources in the Balkans is also considered by some historians to have delayed the launch of the invasion of the Soviet Union by a critical month, which proved disastrous when the German army failed to take Moscow.
Greece itself was occupied and divided between Germany, Italy and Bulgaria, while the King and the government fled into exile in Egypt. First attempts at armed resistance in summer 1941 were crushed by the Axis, but the Resistance movement began again in 1942 and grew enormously in 1943 and 1944, liberating large parts of the country’s mountainous interior and tying down considerable Axis forces. However, political tensions between the Resistance groups resulted in the outbreak of a civil conflict among them in late 1943, which continued until the spring of 1944. The exiled Greek government also formed armed forces of its own, which served and fought alongside the British in the Middle East, North Africa and Italy. The contribution of the Greek war and the merchant navies in particular was of special importance to the Allied cause.
Mainland Greece was liberated in October 1944 with the German withdrawal in the face of the advancing Red Army, while German garrisons continued to hold out in the Aegean Islands until after the war’s end. The country was devastated by war and occupation, and its economy and infrastructure lay in ruins. Greece suffered more than 400,000 casualties during the occupation, and the country’s Jewish community was almost completely exterminated in the Holocaust. By 1946, however, a vicious civil war erupted between the British and American-sponsored conservative government and leftist guerrillas, which would last until 1949.