In April 1941 and after their gains on the western and northern fronts, The German army began its push southwards from Austria. At the same time Rommel was
making headway across North Africa and had reached Benghazi on his way to the Nile. Between the first air raids on Belgrade and Piraeus on 1941-04-06 and the end of the month, German troops had overrun both Yugoslavia and mainland Greece as well as several key Aegean islands. The defeated Greek and allied forces withdrew to Crete. For the Axis, the fact that Greece had to be invaded by Germany was not part of the master plan but the Greeks' defeat of the invading Italian army the previous winter had made it necessary for the Germans to do the job themselves.
With mainland Europe firmly in Axis hands, Crete stood out as the northernmost base from which allied planes could attack continental targets such as the vital oil fields
in Romania. For the Axis it would also provide a stepping stone towards Cyprus and the Nile delta.
After pausing for twenty days and consolidating their positions, the Germans launched Operation Merkur, an airborne invasion of the island that would also be their last of the kind. British intelligence had warning of a buildup of Luftwaffe forces in southern Greece and intercepted related messages. Defences were organised accordingly and ANZAC, British and Greek units on the island were deployed in key regions on the northern coast of the island. Allied air power was limited and based out of three small air strips. After three weeks of air raids, these were in poor condition. Anti-aircraft defences were still solid though.
On the morning of 1941-05-20, about 10000 paratroopers and 750 gliders were thrown at the Cretan defences, concentrated mainly in the north-western part of the island, especially Maleme which was defended by New Zealanders and the most suitable landing point for the surface invasion. Heraklion and Rethymno were also targeted. When the allied anti-aircraft artillery was destroyed, the defenders took to shooting down individual paratroopers as they descended. In two of the three main landing areas, the German paratroopers were pretty much wiped out but they did manage to gain a foothold in three small areas. Paratroopers not caught by the military forces were hunted down and killed by civilians with 19th century firearms and knives. The flower of the Wehrmacht was likely to have its throat slit by a 75-year old peasant woman. It took the Germans seven days to convert the foothold into a realistic tactical advantage and overpower the defences.
The first landing force headed for Souda Bay on the day following the aerial attack was intercepted and destroyed by the British navy. The second landing convoy was stopped until the Germans could clear the waters north of Crete of allied vessels. Several blunders in the air drops and coordination, including one that dropped two companies on top of enemy positions instead of behind enemy lines, took a heavy toll on the invaders.
By the 26th, reinforcements and strong air support had made is possible for the Germans to consolidate their hold on parts of the northern coast and eventually push inland. Partisan resistance in the mountains delayed their arrival on the southern coast until 1941-06-01. By then, allied transport ships had managed to evacuate most of the ground forces to Egypt. Some of the British, Australian and New Zealand troops who got left behind were sheltered by Cretan villagers and were either smuggled off the island later or took part in the resistance.
This was to be the last operation of its kind. Hitler remarked that it was too costly to do again and Winston Churchill had high praise for the Cretan defenders. The additional six weeks it took to take Greece and Crete and thus secure the southern flank delayed the start of Operation Barbarossa, ultimately resulting in the German forces there being caught in the Russian winter before achieving their objective. The battle of Crete was one of the hardest fought German victories of the earlier part of World War II. Altogether, the Axis counted 6000 casualties and the allies 4000.
Original text. This writeup was created on the 60th anniversary of the event.