This was a British naval undertaking by Admiral Sir Andrew Cunningham’s Mediterranean Fleet to support the military convoy delivering personnel and stores to Souda Bay on the north coast of Crete (29 October/2 November 1940).
In 1939 the UK had made a declaration to Greece that in the event of any threat to Greek or Romanian independence, 'His Majesty’s Government would feel themselves bound at once to lend the Greek or Romanian Government…all the support in their power.' Following Italy’s attack on Greece on 28 October 1940, the Greek government invited the UK to fulfil it pledge, and the first practical British effort in this capacity was the deployment of Royal Air Force squadrons, under the command of Air Commodore John D’Albiac, which arrived in November 1940. With Greek government consent, British forces had previously been despatched to Crete on 31 October to guard Souda Bay, enabling the Greek government to redeploy its army’s 5th Division, comprising three Cretan regiments, to the mainland.
At 03.00 on 28 October, the Italian ambassador in Athens had presented the Greek government with Italy’s casus belli, accusing the Greeks with systematic violations of neutrality by allowing their territorial waters and ports to be used by British warships, providing fuelling facilities to British warplanes, and permitting a British intelligence service to be established in Greece. The note had gone on to demand that as a guarantee of Greek neutrality, Italian troops should be given facilities for the occupation of certain unspecified strategic locations in Greece. The Italian ambassador added that Italian troops would begin to cross the frontier at 06.00. Treating this as an ultimatum, Strategós Ioannis Metaxas, the Greek prime minister, rejected the Italian demands, and a few hours later Greece was at war with Italy.
Later in the morning of the same day, the British commanders-in-chief in the Middle East (Cunningham, General Sir Archibald Wavell and Air Marshal Sir Arthur Longmore) met in Alexandria to determine how best to establish a naval fuelling base in Crete. The commanders decided to send an aeroplane to deliver a three-service reconnaissance party to report on local conditions. The Mediterranean Fleet was to sail that night to cover the passage of store ships and auxiliaries to Souda Bay, an a cruiser was allocated for the delivery of the 2/York and Lancaster Regiment, hitherto intended for Malta, which Wavell decided to send. Wavell also agreed to make ready some anti-aircraft and other units.
All the warships currently at sea in the eastern part of the Mediterranean were recalled to refuel, and air reconnaissance from Malta over the Ionian Sea was intensified. One British submarine was patrolling the Strait of Otranto, one was off Taranto, and two Greek submarines were off the Ionian Islands.
At 01.30 on 29 October Cunningham departed Alexandria for the Ionian Sea with the battleships Malaya, Ramillies, Valiant and Warspite, fleet carriers Eagle and Illustrious, and destroyers Dainty, Decoy, Defender, Diamond, Hasty, Havock, Hereward, Hero, Hyperion, Ilex, Janus, Jervis, Juno, Mohawk and Nubian. Late in the evening, at a point to the south of Crete, the heavy cruiser York and light cruisers Gloucester, Orion and Australian Sydney joined the fleet, which continued on a north-westerly course during the following day. At 20.00 on 30 October the fleet was 125 miles (200 km) to the west of Cape Matapan, Crete’s western extremity, covering the passage of the ships bound for Souda Bay. Air reconnaissance reported the Italian fleet to be at Taranto and Brindisi and, as any significant Italian naval effort appeared to be very unlikely, at 16.30 on the following day, some 75 miles (120 km) to the west-south-west of Cape Matapan, Cunningham took Warspite, Illustrious, York, Gloucester, Hasty, Hereward, Hero, Ilex and Jervis back toward Alexandria. The other British ships cruised to the west of Crete before returning safely to Alexandria on 2 November.
It was early in the morning of 29 October that the three-service reconnaissance party arrived in Crete, and during the afternoon of the same day the first convoy departed Alexandria with two ships of the Royal Fleet Auxiliary, two armed boarding vessels, and the netlaying vessel Protector, escorted by destroyers and two anti-aircraft cruisers. This convoy reached Souda Bay on 1 November at about the same time as the arrival of the light cruiser Ajax carrying the 2/York and Lancaster. By the afternoon of the same day the troops and stores had been landed and one anti-submarine net had been laid. The only Italian reaction was attacks by about 15 bombers on Souda and Khaniá on 1 and 2 November, which caused no significant damage.
By 3 November all the anti-submarine defences had been laid and the defences to seaward were being strengthened. 'Action' and 'Assumption' convoys arrived from the 6 November onward with a brigade headquarters, single heavy and light anti-aircraft batteries, one engineer field company, ancillary units, defence stores and supplies for 45 days. It was hoped to be able to operate one fighter squadron for the defence of the base if required, but the only useful airfield on Crete was at Heraklion, some 70 miles (115 km) to the east of Souda Bay and too far distant for aircraft for fighters based there to protect the naval base. The airfield was suitable for use by Gloster Gladiator biplane fighters, but Bristol Blenheim monoplane light bombers could used it in only one direction. Work was therefore immediately started on making it usable by all types of aircraft, and on the preparation of another site about 11 miles (18 km) to the west of Souda Bay.