'Halberd' was the British naval operation to get the GM.2 supply convoy through to Malta from Gibraltar (24/28 September 1941).

The plan was to emulate 'Substance' of July 1941, and thus run the GM.2 convoy of nine fast transport vessels into Malta with supplies and troops (some of the latter being accommodated on the convoy’s close escort vessels) under the overall cover of Vice Admiral Sir James Somerville’s Force 'H', consisting of the battleships Nelson, Rodney and Prince of Wales, the fleet carrier Ark Royal, the light cruisers Edinburgh, Kenya and Sheffield, the light anti-aircraft cruisers Euryalus and Hermione, and the destroyers Cossack, Duncan, Farndale, Fleur de Lys, Foresight, Forester, Fury, Garland, Gurkha, Heythrop, Laforey, Lance, Legion, Lightning, Lively, Oribi, Zulu, Free Dutch Isaac Sweers and Free Polish Piorun.

To facilitate the passage of the convoy, Admiral Sir Andrew Cunningham’s Mediterranean Fleet was to make a demonstration from Alexandria at the other end of the Mediterranean, and under cover of these distractions it was planned that three empty merchant ships were to return from Malta to Gibraltar in MG.2.

The Free Polish, British and Free Dutch submarines Sokol, Trusty and O-21 departed Gibraltar on 19, 20 and 21 September respectively to support 'Halberd' by providing information about Italian naval movements in their patrol areas and, if possible, to intercept the Italian warships. By 24 September the boats Trusty, Upholder, Upright, Urge, Utmost and Free Polish Sokol were in positions to the north of Sicily: Sokol and Trusty were off the island’s north coast, Utmost was on patrol in the northern approach to the Strait of Messina, Upright was on patrol in the north-east approach to the Strait of Messina, Urge was on patrol to the north of Palermo, and Upholder was on patrol to the north of the line between Cape Marittimo and Cape San Vito. The boats O-21, Unbeaten and Ursula were in positions off Cagliari and the Sicilian Straits: Unbeaten was on patrol in the vicinity of Cape Spartivento and Cape del Armi, Ursula was on patrol to the south of the Strait of Messina, and O-21 was on patrol off Cagliari.

The convoy’s ships were the 9,776-ton commissioned Breconshire, 7,539-ton Ajax, 8,063-ton City of Calcutta, 8,039-ton City of Lincoln, 7,347-ton Clan Ferguson, 9,653-ton Clan MacDonald, 11,168-ton Dunedin Star, 12,427-ton Imperial Star and 7,798-ton Rowallan Castle, with escort provided by Force 'H', which was substantially reinforced from Admiral Sir John Tovey’s Home Fleet for this undertaking.

The preliminary movements started on 11 September, when the light cruiser Edinburgh departed Simonstown in South Africa for Gibraltar. On the following day the light cruiser Sheffield departed the Clyde river for Gibraltar with 300 personnel, 20-mm cannon and the appropriate mountings to strengthen the anti-aircraft capability of Force 'H', and arrived on 17 September. The ships for Malta, and their Home Fleet escorts, also departed the Clyde river as the WS.11X convoy on 17 September. The convoy included the transport vessels named above, as well as the liner Stratheden (two days only), commissioned assault ships Queen Emma, Prinses Beatrix, Royal Scotsman and Ulster Monarch, and transport Leinster. The four assault ships were destined for Freetown and Leinster for Gibraltar, and took no part in the Malta convoy. Close escort for the WS.11X convoy was provided by Rear Admiral A. T. B. Curteis’s Group 2 (the battleship Prince of Wales, the light cruiser Kenya, the light anti-aircraft cruiser Euryalus, and the destroyers Garland, Laforey, Lightning, Oribi, Free Dutch Isaac Sweers and Free Polish Piorun. From Gibraltar the destroyers Foresight, Forester, Gurkha, Lance, Legion and Zulu sailed on 18 September to join the escort on the following day.

From 19 September there was a complex reorganisation of the forces at Gibraltar, in part to fuel ships for the Mediterranean passage, in part to reinforce the convoy’s escort on the approach to the Strait of Gibraltar, and in part to confuse Axis observers watching from across the border in neutral Spain. Thus Sheffield sailed on 19 September to join the convoy, followed by the destroyer Lively at 12.00 on the next day. Euryalus and Kenya reached Gibraltar after dark on 22 September, fuelled and departed before dawn to rejoin the convoy, on the following day Prince of Wales with Laforey, Lightning and Oribi did likewise, while the destroyer Cossack and escort destroyers Farndale and Heythrop also sailed to join on 24 September as additional escorts. Finally, on 24 September the battleship Rodney, on passage to the UK from Bermuda, arrived at Gibraltar at 09.00 escorted by Garland, Isaac Sweers and Piorun, which were to fuel, and berthed close to Nelson. This last sailed later that day to join the convoy, with Rodney's escort, leaving Rodney in her berth flying the admiral’s flag and ostentatiously exchanging farewell signals in the hope it would be reported that the movement was a simple exchange of ships en route to the UK.

The cruiser Edinburgh departed at 12.00 to join the convoy, the destroyers Foresight, Forester, Gurkha, Lance, Legion, Lively and Zulu called to fuel and sailed again after dark with the rest of Force 'H' in the form of Rodney, fleet carrier Ark Royal, cruiser Hermione and destroyer Duncan. Finally the oiler Brown Ranger, escorted by the corvette Fleur de Lys, sailed at dusk to provide a fuelling rendezvous within the Mediterranean, and the rescue tug St Day on 26 September to take up a waiting position in case of need.

All the ships which sailed during daylight on 24 September steamed westward, only reversing course to pass eastward through the Strait of Gibraltar after dark. The convoy thus passed through the Strait of Gibraltar at 01.30 on 25 September with the close escort comprising the light cruisers Edinburgh, Kenya and Sheffield, the light anti-aircraft cruisers Euryalus and Hermione, and the destroyers Cossack, Farndale, Foresight, Forester, Heythrop, Laforey, Lightning, Oribi and Zulu together with the reinforced Force 'H' of the battleships Nelson, Prince of Wales and Rodney, the fleet carrier Ark Royal, and the destroyers Farndale, Fury, Garland, Gurkha, Heythrop, Lance, Legion, Lively, Oribi, Free Dutch Isaac Sweers, and Free Polish Garland and Piorun.

After a rendezvous at 09.00 on 25 September, the two groups of warships divided once more and steamed separately until 27 September, when they combined for the most dangerous part of the passage as they approached the Sicilian Narrows.

The ruse was successful and the Italian naval command was at first unaware of the full strength of the fleet and its destination, and as a result it was not until a time early on 27 September that the Italian fleet was ordered to concentrate in preparation for an interception of the convoy. Italian air reconnaissance had spotted the part of the operation to the south of the Balearic islands group on 26 September, and this prompted the Italian submarine deployment, to meet what was believed to be an imminent bombardment of targets on the Italian coast, of Dandolo, Adua and Turchese to the north of Cape Ferrat, and Axum, Serpente, Aradam and Diaspro to the north of Cape Bougaroni, Squalo, Fratelli Bandiera and Delfino to the north of Cape Ferrat, and Narvalo off Cape Bon.

Several motor torpedo boats also patrolled in the area of Pantelleria island.

In the evening Ammiraglio di Armata Angelo Iachino’s Forze Navali da Battaglia (elements of the 1a and 2a Squadre) reached the area to the south-east of Sardinia. The Italian surface force comprised the light cruisers Muzio Attendolo andLuigi di Savoia Duca degli Abruzzi of the 8a Divisione Incrociatori from Palermo together with the destroyers Maestrale, Grecale and Scirocco of the 10^th Flottiglia Cacciatorpediniere to take position off La Maddalena; the battleships Vittorio Veneto and Littorio from Naples with the destroyers Granatiere, Fuciliere, Bersagliere and Gioberti of the 13a Flottiglia Cacciatorpediniere, and Nicoloso da Recco, Pessagno and Folgore of the 16a Flottiglia Cacciatorpediniere, while the heavy cruisers Trieste, Trento and Gorizia from Taranto with the destroyers Corazziere, Carabiniere, Ascari and Lanciere of the 12a Flottiglia Cacciatorpediniere prepared to join them.

In this area the Italian ships still enjoyed the benefits of air cover from bases in Sardinia and Sicily: from Sardinia there were 30 Macchi C.200 monoplane fighters, 20 Fiat CR.42 biplane fighters and 26 Savoia-Marchetti SM.79 and SM.84 torpedo bombers for deployment against the convoy, while from Sicily there were 15 C.200 and three Reggiane Re.2000 fighters, and nine Junkers Ju 87 dive bombers as well as 27 Fiat BR.20, SM.79 and SM.84 bombers, of which three were equipped for torpedo bombing. More Italian aircraft were operational, but were assigned to other missions including the bombing of Malta.

Iachino thought his disposition suitable for the interception of the British convoy and associated naval forces. For lack of fuel, other Italian warships were unable to put to sea.

Ships of the Mediterranean Fleet operating from Alexandria meanwhile began to generate heavy radio traffic in the hope of diverting Luftwaffe attention to possible preparations for a major operation in the eastern Mediterranean. On 24 September Somerville shifted his flag from Nelson to Rodney, and Nelson sailed westward into the Atlantic at 18.15 escorted by Garland, Piorun and Isaac Sweers to give the impression the strength of Force 'H' was being reduced. Nelson then turned back after dusk to join the transport ships of WS.11X, now redesignated as GM.2 as the second convoy from Gibraltar to Malta. Force 'H' separated from the transport ships in the early hours of 25 September so that Axis aerial reconnaissance might come to the conclusion that only Force 'H' was at sea. Fairey Fulmar fighters from Ark Royal provided air cover over the convoy.

Italian aircraft found Force 'H' during the afternoon of 25 September, and assumed the battleships were on a bombardment raid against the Italian coast. A Cant Z.506 floatplane observing Force 'H' at 09.32 on 26 September reported a single battleship with an aircraft carrier incorrectly identified as Furious. As Ark Royal had been seen departing Gibraltar, the Italians assumed Furious might be flying off aircraft to reinforce Malta while Ark Royal's aircraft attacked Genoa. The Italian fleet sailed from Naples to take a defensive position with the 8a Divisione Incrociatori off northern Sardinia, but was ordered not to engage the British fleet unless he had a decisive superiority of forces.

Force 'H' rejoined the GM.2 convoy at 07.10 on 27 September, 16 destroyers forming a curved linear screen ahead of the two columns of merchant and transport ships. The port column was led by the cruiser Kenya, followed by Ajax, Clan MacDonald, Imperial Star, Rowallan Castle and City of Calcutta, and the starboard column was led by the cruiser Edinburgh followed by Clan Ferguson, Dunedin Star, Breconshire and City of Lincoln. Rodney took up position behind the port wing of the screen followed by Prince of Wales, while Nelson took up position behind the starboard wing of the screen followed by Ark Royal in formation with the light anti-aircraft cruisers Euryalus and Hermione. The cruiser Sheffield took position astern of the merchant ships, while the destroyers Piorun and Legion assumed planeguard positions astern of Ark Royal.

Italian aircraft correctly identified Ark Royal at 08.10 and at 10.45 reported the convoy speed as 16 kt. The Italian battleships from Naples made rendezvous with the cruisers from Taranto at 10.40, and were joined by the 8a Divisione Incrociatori at 11.48. The Italian fleet was faster than the battleships of Force 'H', but was inferior to the British force in terms of its firepower. The Regia Aeronautica gave priority to the fighter defence of bomber attacks, and the six fighters providing air cover over the Italian fleet could operate to a radius of only 60 miles (100 km) from their base. Since Italian aircraft had reported only a single British battleship, the Italian fleet received authorisation at 12.00 to engage the British formation, and the Regia Aeronautica was requested to provide increased air cover for the Italian fleet by 14.00. The Regia Aeronautica accordingly launched a force of 28 SM.79 and SM.84 torpedo bombers escorted by 20 CR.42 fighters.

It was at 13.00 on 27 September that air attacks by Italian torpedo bombers started. The first attack was met by Fulmar fighters and heavy anti-aircraft fire, but three bombers pressed through the barrage of starboard wing destroyers to launch torpedoes at Nelson. The British battleship turned to comb the torpedo tracks, but inadvertently steadied on the reciprocal course of a torpedo which struck the port side of the forecastle: holed, the ship took in some 3,750 tons of water, slowing to 15 kt. But this was the speed of the convoy, and the battleship was therefore able to maintain her position in the convoy. The Italian bomber had released its torpedo at a range of only 440 yards (400 m), and endured concentrated anti-aircraft fire from Prince of Wales before being shot down by one of the Fulmar fighters. Six more torpedo bombers and one fighter failed to return from the attack. 'Friendly fire' from Rodney and Prince of Wales was responsible for the British loss of two Fulmar fighters, and a patrolling Fairey Swordfish had been shot down by the Italian fighters before the attack ended at 13.30. The destroyer Laforey was also hit.

The Italian fleet was meanwhile being shadowed by British aircraft from Malta, beginning at 13.07. At 14.30 the Italian fleet was about 40 miles (65 km) from the convoy, but at this time Iachino decided to turn back on learning that the British 'had two battleships, one carrier and six cruisers at sea'. Aircraft from Ark Royal shadowed the Italian fleet from 15.15 to 17.50. CR.42 fighters arrived at 15.30 to provide air cover, but the squadron leader of the first flight was shot down by 'friendly fire' from an Italian destroyer, and two more Italian pilots were lost when another flight of 10 C.200 fighters ran out of fuel and ditched at sea. At 14.46 Prince of Wales, Rodney, Sheffield, Edinburgh and six destroyers, under Curteis’s command, steamed toward the Italian fleet, followed at her best speed by Nelson. Ark Royal also prepared to launch an air attack. The Italian ships were now withdrawing, however, and the planned attack by Ark Royal's aircraft failed as the scout aircraft could not find the Italian ships. The British warships recalled at 17.00 before making contact, and rejoined the convoy at 18.30.

Nelson, Rodney, Prince of Wales and Ark Royal turned to the west in order to return to Gibraltar escorted by Duncan, Fury, Gurkha, Lance, Legion, Lively, Garland, Piorun and Isaac Sweers. As it retired, Force 'H' was attacked by three submarines, of which Adua was sunk by Gurkha and Legion. Another of Ark Royal's Fulmar fighters succumbed to 'friendly fire' from Prince of Wales, increasing the British aircraft losses in 'Halberd' to three Fulmar machines from 'friendly fire' and one Swordfish from Italian action. The Italian aircraft losses were 21 including seven bombers and one fighter from British action, one fighter from 'friendly fire', and 10 fighters from fuel exhaustion.

Euryalus fell in astern of the port column of merchant ships while Sheffield and Hermione joined the starboard column as the remaining destroyers closed into a night steaming formation. The convoy was attacked by a few torpedo bombers. Imperial Star was struck by a single torpedo, and was taken in tow by Oribi.

Italian MAS motor torpedo boats had been deployed through the Strait of Messina, but failed to find the convoy.

After towing had proved impossible at the speed required, Heythrop took off Imperial Star's 300 troops and crew, and the ship was left burning and sinking after her scuttling charges had been fired, but finally she was shelled and sunk by Oribi.

During the night the cruiser Hermione closed Pantelleria island and carried out a gunfire bombardment to render the island''s airfield at least temporarily unserviceable and thereby reduce the Italian air threat when the convoy reached Malta; the cruiser also dropped smoke floats and generally created the impression that the convoy was passing the island, although it was in fact well to the north. No further attacks developed, and at dawn fighters from Malta started to provide continuous air cover.

At 08.30 Euryalus, Hermione, Kenya and Sheffield went on ahead of the convoy to reach Malta at 11.20. The cruisers disembarked their troops and stores and departed once more at 18.30. The convoy, escorted by Edinburgh and the destroyers, arrived early in the afternoon without further loss, bringing 85,000 tons of invaluable supplies to the island.

During this operation, Melbourne Star sailed from Malta alone on 26 September and reached Gibraltar without incident on 29 September. City of Pretoria and Port Chalmers sailed at the fall of night on 27 September, briefly with a local corvette escort, and then steamed together for Gibraltar. During the night Port Chalmers drove off an attack by Italian torpedo craft, and at dawn the ships separated and went on alone under French colours: Port Chalmers reached Gibraltar on 30 September without suffering further attack, and was followed some hours later by City of Pretoria, which had beaten off an attack by three torpedo bombers and evaded two probable submarine attacks.

The 'Halberd' convoy escort, having sailed from Malta at dusk on 28 September, returned to Gibraltar along the North African coast and was attacked on several occasions by submarines. No damage ensued from these.

The main body of Force 'H' returned to Gibraltar at various times during 30 September, the other ships by 08.30 on 1 October, and the reinforcements commenced their return to the UK on the same day.

Breconshire, lying empty at Malta since her arrival in the MG.1 convoy, was ordered to Alexandria and sailed on 5 December escorted by the destroyers Kimberley and Kingston, with more distant support from the cruisers Ajax and Neptune and destroyer Lively. The combined force suffered air attack on 6 December, but sustained no damage, and later that day the covering force separated from Breconshire and her escort.

The cruisers Carlisle, Galatea and Hobart, together with the destroyer Hotspur, sortied from Alexandria and met the convoy on 7 December, and all the ships reached Alexandria on 8 December.

Just one week later, Breconshire had taken on a new cargo and departed Alexandria once again for Malta, this time with the escort of the cruisers Carlisle, Euryalus and Naiad, and the destroyers Decoy, Havock, Hasty, Jervis, Kimberley, Kingston, Kipling and Nizam.

Carlisle was detached late on 16 December, and the cruisers Aurora and Penelope, together with the destroyers Lance and Lively, of the Malta-based Force 'K' sailed to meet the incoming ships at first light on 17 December. Several air attacks were made during that afternoon, and reports were also received that the Italian fleet was at sea. Just before dusk the Italian ships were sighted, and Breconshire, escorted by Decoy and Havock, was ordered away from their approach, the remainder of the escort preparing for a night action. In the ensuing brief action in the dark, the British warships maintained touch with the Italian force and contact between the British ships became fragmented, with the result that no close encounter took place.

Breconshire, her escort and Force 'K', augmented by the cruiser Neptune and destroyers Jaguar and Kandahar, reached Malta on 18 December, while the other ships returned to Alexandria.