'Demon' (i) was the British naval evacuation of Allied forces from mainland Greece at the end of the Axis conquest of the country in 'Marita' (24 April/1 May 1941).

'Marita' had started on 6 April, and very heavy air attacks were immediately launched on Piraeus, port of Athens and the main maritime gateway into and out of Greece. During that night the 7,529-ton British merchant vessel Clan Fraser, loaded with explosives, was hit, caught fire and blew up, the explosion destroying 10 other ships (totalling more than 41,000 tons) and effectively putting the port out of action. It was a major blow to the Allied plans for the defence of Greece for it deprived the British of the only reasonably equipped base through which essential reinforcements and supplies could be delivered to the army, whose continued existence as a fighting force now depended on the use of small and poorly equipped ports accessed only by poor road and rail links.

The destruction of Piraeus also deprived the Greek navy of its main base and, on 24 April the surviving ships were allocated to Admiral Sir Andrew Cunningham, commanding the Mediterranean Fleet, and arrived in Alexandria: these Greek ships included the old cruiser Giorgios Averoff, a repair ship, six large destroyers, two torpedo boats and six submarines; a Yugoslav submarine and two motor torpedo boats also reached Alexandria, but none of Yugoslavia’s three large destroyers got away at the end of Germany’s 'Undernehmen 25' conquest of that country undertaken at much the same time as 'Marita'.

By 16 April it was clear that the position of the British and commonwealth forces ashore in Greece could not be maintained for much longer in the face of rampant German land successes, and that an evacuation would therefore be needed to return to Egypt as much of the expeditionary forces as could be salved.

The planning of 'Demon' was taken in hand immediately, and on 21 April the British war cabinet approved the evacuation. It had originally been thought that the evacuation would take place on 29 April, but the rapid success of the German forces on the Greek mainland soon dictated that the date be brought forward to 24 April and, from the very start it was recognised that this would be an extremely difficult undertaking. The Germans' complete air superiority had caused chaotic conditions on land, communications were constantly breaking down, and intelligence was both vague and unreliable. Air protection of only an inadequate capability could be provided over the embarkation ports and beaches, and this meant that work could be carried out only during the hours of darkness: the transport vessels could not arrive until one hour after dark, and had to be clear of the coast by 03.00 on the following morning.

About 20 minor ports were selected for the evacuation, but in the event only eight of these were used.

All of Cunningham’s light forces, except those recently detached to work from Malta, were committed to 'Demon': six cruisers (the light cruisers Ajax and Orion, and the light anti-aircraft cruisers Calcutta, Carlisle, Coventry and Phoebe), 20 destroyers (Stuart, Voyager, Vendetta, Waterhen, Vampire, Wryneck, Diamond, Decoy, Defender, Griffin, Hasty, Havock, Hero, Hotspur, Hereward, Isis, Nubian, Kandahar, Kingston and Kimberley), three sloops (Grimsby, Flamingo and Auckland), two corvettes (Hyacinth and Salvia), six landing craft, three 'Glen' class commissioned fast transports (9,919-ton Glengyle, 9,809-ton Glenroy and 9,784-ton Glenearn recently sent out as assault ships for the commando forces in the Mediterranean and Middle Eastern theatres), 19 freighters and a number of smaller vessels.

The plan was based on the provision of eight mercantile transports, which were to be brought close inshore to the locations at which they would embark the soldiers ferried out to them by small ships and craft. To make such forces available, Cunningham was forced to remove the ships allocated to the communications of the British and commonwealth forces fighting in the Western Desert, and also left his own battle fleet without a destroyer screen.

The evacuation was commanded by Vice Admiral H. D. Pridham-Wippell flying his flag in the light cruiser Orion, and the British army units to be evacuated congregated at Raftina and Raftis in Attica, and at Nafplio, Monemvasia and Kalamata in the Peloponnese. Though the task allocated to the Mediterranean Fleet was the rescue of only about 20% of the number of troops brought back from Dunkirk in 'Dynamo', the task faced difficulties even more serious than those faced by 'Dynamo'. The sea passages to and from the points of embarkation were far longer, for example, and there were no well-equipped bases to which damaged ships could easily return for swift repair, rapid replenishment of fuel, ammunition and provisions, and immediate replacement of casualties. Instead of having a united population and the resources of a major industrial nation supporting it, the Mediterranean Fleet had to work from a base in Egypt, a wavering and neutral country 450 miles (725 km) away. Souda Bay on the northern side of Crete and Alexandria on Egypt’s Mediterranean coast offered facilities wholly inferior to those which had been available to the 'Dynamo' forces at Chatham, Dover and Portsmouth. Perhaps most decisively, whereas 'Dynamo' had been provided with a useful though not impenetrable air umbrella by the Supermarine Spitfire and Hawker Hurricane single-engined fighters of Air Chief Marshal Sir Hugh Dowding’s RAF Fighter Command, 'Demon' was to all intents and purposes without air protection of any type over the coasts and inshore waters of Greece.

Thus the sailors of the Mediterranean Fleet were faced with the task of aiding their army brethren in the full knowledge that the Luftwaffe would be in undisputed possession of the skies and would do its utmost to prevent the evacuation.

The evacuation started on the night of 24/25 April and continued for five nights. Then for two more nights stragglers were successfully lifted from the southern tip of the Peloponnese. Moreover the seizure of the Corinth Canal bridge by a German airborne force on 26 April endangered the southern evacuation points at a time far earlier than had been expected. A highly hazardous task thus became a critically dangerous undertaking. Nearly 1,300 soldiers were embarked from Piraeus before the evacuation proper had started in Raftis, Megara and Nafplio, when Calcutta, Salvia and Glengyle carried 5,750 men, including 1,000 wounded, to Souda Bay in Crete, and the transport Thurland Castle brought 3,500 men and 100 nurses from Megara to Souda Bay. Phoebe, Stuart, Voyager, Hyacinth, Glenearn and Ulster Prince ferried others to Nafplio. Glenearn was attacked by a Junkers Ju 87 single-engined dive-bomber and damaged, but was still able to disembark some 5,100 personnel. Ulster Prince ran aground and was bombed on the following day. Voyager embarked a few dozen nurses.

On 25 April Pennland and Thurland Castle disembarked 5,000 persons embarked at Megara after a passage covered by Coventry and five destroyers. Heading back to the mainland, Pennland was twice attacked by bombers and finally sunk. Griffin and three other destroyers assumed the lost ship’s transport role and brought out 6,000 personnel.

The climax of 'Demon' took place on the night of 26/27 April, when 27,000 men were awaiting evacuation. On 27/28 April the light cruiser Ajax and three destroyers won another 4,750 soldiers from Raftis and Nafplio, and on the following night a further 4,320 from Monemvasia. Escorted by three destroyers, Glengyle reached Rafina, and the transport Salween with two destroyers reached Raftis. The transports Slamat and Khedive and the landing ship Glenearn, escorted by Calcutta and three destroyers, reached Nafplio, and the transports Dilwara, City of London and Costa Rica, accompanied by Phoebe and four destroyers, arrived in Kalamata. The ships lifted 22,500 men (8,200 from Rafina and Raftis, 4,500 from Nafplio and 9,800 at Kalamata). Glenearn was hit by bombs and had to be towed to Crete by Griffin. This further reduced the available lift capability and meant that several thousand men had to be left on the beach as Glenearn, damaged still more by the attacks of several Ju 87 dive-bombers, was late in arriving and could send only some of its landing craft to the beach at Nafplio.

Loaded with troops, Slamat was bombed and machine gunned, and caught fire. Diamond and Wryneck managed to take most of the survivors on board, but were themselves later attacked and sunk: of the total of more than 1,000 persons on the three ships, only 50 were saved. Phoebe and the convoy she was escorting were attacked in Kalamata. Here the transport Costa Rica, with 2,400 troops on board, was hit by a bomb and unable to steam, but managed to transfer her load to Defender, Hero and Hereward before sinking.

The light cruiser Perth, anti-aircraft cruiser Phoebe and nine destroyers were sent to Kalamata on 28/29 April in the hope of bringing off some 10,000 men. When the ships arrived they found that a small German column had penetrated to the harbour and captured the naval officer charged with organising the evacuation. Though control was, in fact, quickly regained in the town, the embarkation arrangements could not be restored in the short time available, and the ships sailed prematurely after rescuing only 450 men from adjacent beaches.

The last stage of the 'Demon' evacuation was undertaken from Monemvasia, where Ajax loaded 4,300 men, and from the island of Kithira, where three corvettes collected 1,000 soldiers. Finally, on the night of 30 April/1 May, Hotspur and Havock collected 700 British and Palestinian troops from the island of Milos.

The final total of men brought away from Greece, mostly to Crete, was 50,732, representing about 80% of the number originally carried to Greece in 'Lustre'.

During 'Demon', the warplanes of General Wolfram Freiherr von Richthofen’s VIII Fliegerkorps were notably successful: Pennland, Slamat and Costa Rica were all sunk by bombs, and Ulster Prince was lost in Nafplio harbour. Patrols between Crete and Egypt by the Italian submarines Settembrini, Fisalia, Ondina, Nereide and Turchese achieved no success.

Though many men had been evacuated, the British forces had been forced to abandon all their heavy weapons, equipment and aircraft, while the evacuation force had lost four ships and many others were damaged, several of them most severely. By 4 May the surviving lighter warships of the Mediterranean Fleet had managed to reassemble at Alexandria for repairs and a brief period of rest but, as a portent for the immediate future, the Germans had already stretched their grasp to the principal Greek islands, thereby ensuring German control of the Aegean Sea and of the approaches to the Dardanelles, and raising the spectre of German expansion to Crete, Cyprus, Syria and the Middle East.