Fascist Italy had initially declared war and invaded Greece in October 1940, but the Hellenic Army managed to push back the invading forces into neighboring Albania, then an Italian protectorate. Nazi Germany intervened on its ally's behalf in southern Europe. While most of the Hellenic Army was dislocated on the Albanian front to fend off the relentless Italian counter-attacks, a rapid German "Blitzkrieg" campaign commenced in April 1941, and by June (with the conquest of Crete) Greece was defeated and occupied. The Greek government went into exile, and an Axis collaborationist puppet government was established in the country. Greece's territory was divided into occupation zones run by the Axis powers, with the Germans administering the most important regions of the country themselves, including Athens, Thessaloniki and the strategic Aegean Islands. Other regions of the country were given to Germany's partners, Italy and Bulgaria.