The Battle of Greece (also known as Operation Marita, German: Unternehmen Marita) is the common name for the invasion and conquest of Greece by Nazi Germany in April 1941. Greece was supported by British Commonwealth forces, while the Germans' Axis allies Italy and Bulgaria played secondary roles. The Battle of Greece is usually distinguished from the Greco-Italian War fought in northwestern Greece and southern Albania from October 1940, as well as from the Battle of Crete fought in late May. These operations, along with the Invasion of Yugoslavia, comprise the Balkans Campaign of World War II.

The Balkans Campaign began with the Italian invasion of Greece on 28 October 1940. Within weeks, the Italians were driven out of Greece and Greek forces pushed on to occupy much of southern Albania. In March 1941, a major Italian counterattack failed, and Germany was forced to come to the aid of its ally. Operation Marita began on 6 April 1941, with German troops invading Greece through Bulgaria in an effort to secure its southern flank. The combined Greek and British Commonwealth forces fought back with great tenacity, but were vastly outnumbered and out-gunned, and finally collapsed. Athens fell on 27 April, however the British managed to evacuate about 50,000 troops. The Greek campaign ended in a quick and complete German victory with the fall of Kalamata in the Peloponnese; it was over within 24 days. The conquest of Greece was completed through the capture of Crete a month later. Greece remained under occupation by the Axis powers until October 1944.

Greece ⁱ/ˈɡriːs/ (Greek: Ελλάδα, Ellada, IPA: [eˈlaða] ( listen) historically in Katharevousa and Ancient Greek: Ἑλλάς, Hellas, IPA: [eˈlas] and [helːás] respectively), officially the Hellenic Republic (Ελληνική Δημοκρατία, Elliniki Dimokratia, IPA: [eliniˈci ðimokraˈtia]), is a country in Southern Europe, politically considered part of Western Europe.Athens is the capital and the largest city in the country (its urban area also including Piraeus). The population of the country is around 11 million.

Greece has land borders with Albania, the Republic of Macedonia and Bulgaria to the north, and Turkey to the east. The Aegean Sea lies to the east of mainland Greece, the Ionian Sea to the west, and the Mediterranean Sea to the south. Greece has the 11th longest coastline in the world at 13,676 km (8,498 mi) in length, featuring a vast number of islands (approximately 1,400, of which 227 are inhabited), including Crete, the Dodecanese, the Cyclades, and the Ionian Islands among others. Eighty percent of Greece consists of mountains, of which Mount Olympus is the highest at 2,917 m (9,570 ft).