Greece was invaded by Italy on 28 October 1940 and subsequently joined the Allies. The Greek Army managed to stop the Italian offensive from Italy's protectorate of Albania, and Greek forces pushed Italian forces back into Albania. However, after the German invasion of Greece in April 1941, German forces managed to occupy mainland Greece and, a month later, the island of Crete. The Greek government went into exile, while the country was placed under a puppet government and divided into occupation zones run by Italy, Germany and Bulgaria. From 1941, a strong resistance movement appeared, chiefly in the mountainous interior, where it established a "Free Greece" by mid-1943. Following the Italian capitulation in September 1943, the Italian zone was taken over by the Germans. Axis forces left mainland Greece in October 1944, although some Aegean islands, notably Crete, remained under German occupation until the end of the war.