Some 28 Italian divisions participated in the Balkan invasions. The coast of Yugoslavia was occupied by the Italian Army, while the rest of the country was divided between the Axis forces (a German and Italian puppet State of Croatia was created, under the nominal sovereignty of Prince Aimone, Duke of Aosta, but actually governed by the Croatian fascist Ante Pavelić). The Italians assumed control of most of Greece with their 11th Army, while the Bulgarians occupied the northern provinces and the Germans the strategically most important areas. Italian troops would occupy parts of Greece and Yugoslavia until the Italian armistice with the Allies in September 1943.
when did italy join the allies in ww2
September 1943