The occupation of Greece by the Axis Powers began in April 1941 after Nazi Germany invaded the Kingdom of Greece to assist its ally, Italy, in their ongoing war that had started in October 1940. Following the conquest of Crete, the entirety of Greece was occupied starting in June 1941. The occupation of the mainland lasted until Germany and its ally Bulgaria withdrew under Allied pressure in early October 1944, with Crete and some other Aegean islands being surrendered to the Allies by German garrisons in May and June 1945, after the end of World War II in Europe.

The Greco–Italian War, also called the Italo–Greek War, Italian Campaign in Greece, and the War of '40 in Greece, took place between the kingdoms of Italy and Greece from 28 October 1940 to 23 April 1941. This local war 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.