This was a British operation to reinforce the Greek air force in the fighting against the Italian 'Emergenza G' invasion with RAF fighter and bomber squadrons of Air Chief Marshal Sir Arthur Longmore’s Middle East air strength (15 November/December 1940).
The units despatched to Greece began with No. 30 Squadron flying a mixed force of Bristol Blenheim light bombers and Gloster Gladiator biplane fighters, and followed with Nos 84 and 211 Squadrons flying Blenheim bombers, and No. 80 Squadron flying Gladiator fighters. No. 112 Squadron, which was scheduled for re-equipment, also sent its obsolescent Gladiator fighters for service with the Greek air force.
This diversion of strength from the Western Desert, followed by others in the early months of 1941, had unfortunate results for the British and commonwealth forces operating against the Italian forces based in Libya. While the aircraft involved could be flown to Malta, their support personnel, spares and ammunition had to be delivered by military convoys. On 29 September Admiral Sir Andrew Cunningham’s Mediterranean Fleet despatched a major force, comprising the battleships Malaya, Ramillies, Valiant and Warspite, fleet carrier Eagle, heavy cruiser York, and light cruisers Ajax, Gloucester, Orion and Australian Sydney, as well as a sizeable force of destroyers, to cover the passage of these military convoys to Souda Bay on the north coast of Crete.
On 1 November these British warships came under heavy and sustained attacks while deployed with other British ships in the Aegean Sea to provide protection against Italian air and submarine attack, but all the ships returned to base.
'Barbarity' proper began on 15 November, and this day indicated the very considerable effort which the British had to make to effect the reinforcement of Greece. On this first day, the light cruisers Ajax and Orion departed Alexandria to take general control of 'Barbarity' and to call at Souda Bay, Piraeus and Kandia as necessary. The light anti-aircraft cruiser Coventry, together with the destroyers Mohawk, Nubian and Australian Vampire, departed Alexandria with three merchant ships in the form of the 10,492-ton Clan Macaulay, 10,733-ton Imperial Star and 11,069-ton Nieuw Zeeland. The 10,474-ton Johan de Witt, escorted by the Australian destroyer Waterhen, joined the convoy at sea. The AN.7 convoy of five transports carrying 830 men and 710 vehicles, together with a bulk petrol carrier, departed Alexandria and Port Said, escorted by trawlers, the light anti-aircraft cruiser Calcutta and destroyer Ilex. The light cruisers Ajax and Orion covered the convoy to Piraeus, where it arrived on 19 November. The trawlers returned to Souda Bay, and Calcutta and Ilex to Alexandria.
The heavy cruisers Berwick and York, light cruisers Glasgow and Gloucester of the 3rd Cruiser Squadron, and Australian light cruiser Sydney departed Alexandria with 3,400 troops for Piraeus.