Why did Italy fight against the Allied powers during World War II?

Italy fought against the Allied powers during World War II primarily due to the expansionist ambitions of the Fascist regime under Benito Mussolini, who sought to acquire territory in Africa and the Mediterranean.1

Following Italy's invasion of Ethiopia in 1935, the country faced diplomatic isolation and sanctions from the League of Nations, which pushed Mussolini to align with Nazi Germany. This relationship was formalized through the Rome-Berlin Axis in 1936 and the Pact of Steel in 1939, a military alliance that committed both nations to mutual support in conflicts.123

Although Italy initially remained neutral when the war began in 1939, Mussolini declared war on Britain and France on June 10, 1940. He was motivated by the belief that the war was nearing its end and hoped that joining Germany would allow Italy to secure territorial spoils and establish dominance in the Mediterranean.145