Mussolini supported Hitler at the Munich conference in 1938, and increasingly became an ally of the Germans. Although Italy was militarily weak and unprepared, Mussolini declared war on France once it had been defeated by Germany in 1940. Italy then signed an official "Axis" alliance with Germany and Japan in September 1940.
Now at war with Britain, Italy sent an invasion army into Egypt. However, British warplanes severely damaged half the Italian fleet at Taranto on November 11, 1940. The British counterattack in Egypt was successful, reaching deep into Libya. The British, with only 555 killed, captured 130,000 Italian prisoners. In Ethiopia Italy scored some initial gains but by spring 1941 the British counterattack destroyed the Italian base in Ethiopia. Germany now had to rescue its weak Italian ally, and sent its tank forces to north Africa to fight the British. The British took control of the Mediterranean, and cut off reinforcements and supplies to the Germans and Italians, leading to their surrender in early 1943.
The Allied Powers invaded Sicily in August 1943 and then invaded the peninsula in September. Mussolini and his Fascists lost power after these debacles, as the King brought in a new government under Pietro Badoglio. Italy now joined the Allies. However, Germany had invaded and seized control of Italy north of Naples, rescued Mussolini from prison, and installed him as the nominal leader of a puppet state, the Italian Social Republic. The Italian campaign from 1943 to 1945 involved mountainous warfare, with little movement and high casualties. The civilians suffered heavily. Rome fell on June 4, 1944, and the Allies soon reached Florence, but could make no further progress. The Allied breakthrough came in April 1945, as the German defenses collapsed. Mussolini try to flee to Switzerland, but was captured and executed by Communist Italian partisans on April 28, 1945.