On the morning of May 20, 1941, Germany launched an airborne invasion of Crete under the code name Operation Merkur (Mercury).
Prelude
The British had occupied Crete when Italy invaded Greece in October 1940. After the German intervention in Greece, Allied troops were evacuated, some to Crete. The defense consisted of 10,000 Greek militia and 30,000 British, Australian, and New Zealand troops under New Zealand General Bernard Freyberg, though many lacked heavy equipment. The RAF withdrew its planes to Egypt, leaving the Luftwaffe with air superiority.
The Battle
On May 20, German paratroopers landed near Maleme and Chania after 3 hours of heavy bombing. The landings were preceded by heavy losses — paratroopers jumped into heavy infantry fire and were unable to recover weapons landed by separate parachutes. The next wave at Rethimnon and Heraklion ran into even heavier fire.
On May 21-22, the Royal Navy intercepted German naval convoys, but Luftwaffe attacks drove British ships away. By May 22, enough control had been established for the 5th Mountain Division to land at Maleme airfield. From that point, the Germans could constantly fly in additional troops.
Conclusion
The Germans captured the island in 10 days but at heavy cost: 6,600 German soldiers, including one in four paratroopers, lay dead. About 17,000 Allied soldiers were evacuated by the Royal Navy between May 28-31. Hitler was so shocked by losses that he never approved another large-scale airborne operation. Ironically, the Allies learned from the lessons and put them to good use at Normandy.