Greek cruiser Elli (1912) in the context of "Greco-Italian War"

The Greco-Italian War, also called the Italo-Greek War, took place between Italy and Greece from 28 October 1940 to 23 April 1941. This conflict began the Balkans campaign of World War II between the Axis powers and the Allies, and eventually turned into the Battle of Greece with British and German involvement. On 10 June 1940, Italy declared war on France and the United Kingdom. By September 1940, the Italians had invaded France, British Somaliland and Egypt. This was followed by a hostile press campaign in Italy against Greece, accused of being a British ally. A number of provocations culminated in the sinking of the Greek light cruiser Elli by the Italians on 15 August. On 28 October, Mussolini issued an ultimatum to Greece demanding the cession of Greek territory, which the Prime Minister of Greece, Ioannis Metaxas, rejected.

Italy's invasion of Greece, launched with the divisions of the Royal Army based in Italian-controlled Albania, badly armed and poorly commanded, resulted in a setback: the Italian forces encountered unexpectedly tenacious resistance by the Hellenic Army and penetrated only a few kilometers into Greek territory and had to contend with the mountainous and muddy terrain on the Albanian–Greek border. With British air and material support, the Greeks stopped the Italian invasion just inside Greek territory by mid-November and subsequently counter-attacked with the bulk of their mobilized army to push the Italians back into Albania – an advance which culminated in the Capture of Klisura Pass in January 1941, a few dozen kilometers inside the Albanian border. The defeat of the Italian invasion and the Greek counter-offensive of 1940 have been called the "first Axis setback of the entire war" by Mark Mazower.