Hitler’s forces attacked Greece and Yugoslavia on April 6, 1941. The Metaxas Line, fortresses on the Greek-Bulgarian border, stopped the Germans until Yugoslavia fell on April 17. Then the Germans could move into Greece from Yugoslavia and surrounded the Greek positions.
Hitler still had to shift forces preparing for the invasion of Russia to collapse the Greek Resistance. The whole Peloponnesian peninsula was overrun and Athens fell on April 27.
British Commonwealth forces numbering 43,000 were evacuated to Crete and to Egypt. Lacking dominant sea power, the Germans looked for a way to eliminate Crete as a threat. German Fallschirmjäger parachute corps commander Kurt Student had the answer. He began planning an invasion of Crete by air.
Greece was occupied by the Germans until 1944. They withdrew their forces as they needed men and materiél to replace their losses in France and the Soviet Union. Almost immediately the Greeks split into pro-Western and Communist factions, which began a civil war. Churchill, who saw Greece as the foundation of democracy, sent in British troops to keep order. After World War II the United States supported the pro-Western Greeks in a protracted civil war.