'MC4' was a British naval undertaking by Admiral Sir Andrew Cunningham’s Mediterranean Fleet to secure the safety of the 'Excess' convoy from Gibraltar to Piraeus, the MW.5½ Malta to Alexandria convoy and the ME.5½ and ME.6 convoys from Malta to Alexandria convoys (6/13 January 1941).

Italy’s entry into the war on 10 June 1940, on the side of Germany, brought World War II to the Mediterranean Sea, where the Italian air force was well positioned in Italy and North Africa to interdict the UK’s traditional sea route to the Indian Ocean and thus the Far East and Australasia, while the availability of the Italian navy approximately tripled the numbers of battleships, cruisers and submarines available to the Axis powers in challenging British naval power. Up to this time the Royal Navy had been prepared to defend the eastern basin of the Mediterranean and the French navy to control the western basin of the same sea, but then the defeat of France, as signalled by the armistice which became effective on 25 June, took the French out of the equation. From its primary bases at Gibraltar and Alexandria the Royal Navy attempted to convoy the shipping needed to sustain Malta as the main British bastion in the central Mediterranean, where it was sited as an 'unsinkable aircraft carrier' and naval base athwart the primary maritime line of supply linking metropolitan Italy and her colony of Libya in North Africa. As Italy attacked Egypt from Libya in September 1940 and Greece from Albania in October 1940, the Royal Navy maintained most of Admiral Sir Andrew Cunningham’s Mediterranean Fleet at Alexandria while Vice Admiral Sir James Somerville’s Force 'H' at Gibraltar was used for raids. Early Allied successes in November 1940 included the Greek halting of the Italian offensive from Albania, and the disabling of the Italian battleships Littorio, Conte di Cavour and Caio Duilio in the 'Judgement' pioneering carrierborne air attack on the harbour of Taranto, and these generated both the incentive and the opportunity to resupply Malta and to bolster Greece.

Thus arrangements for the despatch of a military convoy to Malta and through to the eastern basin of the Mediterranean Sea at a time early January 1941 were formulated by the Admiralty at a time early in December 1940. The plan called for 21 ships to depart the UK on 18 December for the Middle East: 16 of these were to make the considerably longer but comparatively safe passage round the Cape of Good Hope, and the other five were to undertake the shorter but altogether more dangerous passage through the Mediterranean. These latter five ships were the heart of the 'Excess' convoy, and comprised the 7,264-ton Clan Cumming, 9,653-ton Clan MacDonald, 9,228-ton Empire Song and 10,917-ton Northern Prince carrying weapons, equipment and supplies to Piraeus in Greece, and the 11,063-ton Essex carrying 3,000 tons of seed potatoes, 4,000 tons of ammunition and 12 crated Hawker Hurricane fighters to Malta. However, Northern Prince was driven ashore in a gale a few days before the convoy sailed with Force 'H' from Gibraltar on 7 January, and her non-arrival at the Piraeus proved to be a serious matter for the Greek army as the ammunition and essential supplies for Greek powder factories she was carrying were sorely needed.

The Admiralty entrusted the planning for the execution of the the Mediterranean convoy to Somerville and Cunningham, the commanders of the Gibraltar-based Force 'H' and Alexandria-based Mediterranean Fleet respectively, and the result was the 'MC4' operation designed primarily to nourish the war industry of Greece and and the survivability of Malta .

Advantage of the operation was taken by Cunningham to send the MW.5½ fast convoy (10,492-ton Clan Macaulay and 9,776-ton commissioned Breconshire) from Alexandria to Malta with much urgently needed matériel, and two convoys from Malta to Alexandria as ME.5½ and ME.6. The former comprised the 9,816-ton Lanarkshire and 12,435-ton Waiwera, and the latter the 6,054-ton Devis, 9,351-ton Norwegian Hoegh Hood, 5,916-ton fleet auxiliary oiler Plumleaf, 8,319-ton Pontfield, 3,338-ton Rodi, 7,406-ton Trocas and 1,587-ton Volo). The ships of the ME.6 convoys were to steam with the Aegean portion of 'Excess' until reaching the area to the south of Crete.

The planners rightly decided that there were three critical stages in the passage of the 'Excess' convoy: these were the sectors from Sardinia to the Narrows, a distance of 150 miles (240 km) to be covered between 12.00 and 20.00 on 9 January; through the Narrows, a distance of 170 miles (275 km) to be covered between 20.00 on 9 January and 08.00 on 10 January; and from the Narrows to Malta, a distance of 125 miles (200 km) to be covered between 08.00 and 17.00 on 10 January.

The warships to cover this complex operation were divided into six groups. Force 'A' comprised the battleships Valiant and Warspite (flying Cunningham’s flag), the fleet carrier Illustrious (flying Rear Admiral A. L. St G. Lyster’s flag) and the destroyers Dainty, Gallant, Greyhound, Griffin, Jervis, Mohawk and Nubian, and was to sortie from Alexandria to cover the 'Excess', MW.5½ and ME.6 convoys in the area to the east of the Skerki Bank. Rear Admiral E. de F. Renouf’s Force 'B' comprised the light cruisers Gloucester and Southampton, and the destroyers Ilex and Janus, and was to deliver some 500 soldiers and airmen from the Aegean to Malta, and then join the 'Excess' convoy. Force 'C' comprised the light anti-aircraft cruiser Calcutta and the destroyers Defender and Diamond, and was to escort MW.5. Vice Admiral H. D. Pridham-Wippell’s Force 'D' comprised the heavy cruiser York and the light cruiser Orion, and was to depart Alexandria with the corvettes Gloxinia, Hyacinth, Peony and Salvia, as well as the replenishment oiler Brambleleaf, to be joined by the light cruisers Ajax and Australian Perth from Souda Bay in Crete. Force 'F' was to comprise the light anti-aircraft cruiser Bonaventure carrying 400 soldiers and airmen to Malta, and the destroyers Hasty, Hereward, Hero and Jaguar, and was to depart Gibraltar as escort for the 'Excess' convoy. Finally, Force 'H' was to comprise the battleship Malaya, battle-cruiser Renown (flying Somerville’s flag), the fleet carrier Ark Royal carrying six Fairey Swordfish torpedo bombers for Malta, the light cruiser Sheffield and the destroyers Faulknor, Firedrake, Forester, Fortune and Fury, and was to depart Gibraltar as cover for the 'Excess' convoy.

The escorts for the first critical stage were Malaya, Renown, Ark Royal, Gloucester, Sheffield, Southampton, Bonaventure and 12 destroyers; for the second stage Gloucester, Southampton, Bonaventure, and five destroyers; and for the third stage Valiant, Warspite, Illustrious, Gloucester, Southampton and Bonaventure.

It was also arranged that three submarines were to patrol to the north of the convoy’s route in the Sardinian Channel, and that the Malta to Egypt convoys were to be covered by the heavy cruiser York, light cruisers Ajax, Orion and Australian Perth, and light anti-aircraft cruiser Calcutta of the 7^th Cruiser Squadron, two destroyers and four corvettes.

The Royal Air Force furnished anti-submarine patrols from Gibraltar and air reconnaissance of Italian ports from Malta, and during the morning of 8 January an RAF report placed two or three Italian battleships at Naples, three cruisers at Messina and four cruisers at Taranto. Somerville relied on the reconnaissance of his carrierborne aircraft for information of the presence of Italian surface vessels in the area to the south and east of Sardinia.

However, the primary threat to the British undertaking was Axis air power, and in this regard a potentially decisive factor was the currently ongoing transfer of the 500 or so aircraft of a specialised maritime warfare formation, General Hans Geisler’s X Fliegerkorps from Norway to bases in Sicily.

On 6 January the 'Excess' convoy departed Gibraltar, feinting first to the west and thus into the Atlantic before turning to the east and thus toward Malta after darkness had hidden it from the gaze of Axis agents near Gibraltar at Algeciras in neutral Spain. On the following day Force 'H' also departed Gibraltar to cover the 'Excess' convoy, Force 'A', Force 'D' and the MW.5 convoy with Force 'C' departed Alexandria, and Force 'B' sailed from the Aegean Sea toward Malta. Force 'A' was located by Italian air reconnaissance during the afternoon of this day. On 8 January, the ships of Force 'B' landed their passengers in Malta and proceeded to the west in order to meet the 'Excess' convoy. Vickers Wellington medium bombers attacked Naples during this period, damaging Giulio Cesare with three near misses, and also causing Vittorio Veneto, Italy’s only operational battleship, to be pulled back from the oncoming convoys.

On 9 January, Force 'A' was joined by Force 'D' and Sydney some 240 miles (385 km) to the south-east of Malta. Force 'B' joined the 'Excess' convoy which, with the ships of Force 'H', was located by Italian aircraft in a position some 25 miles (40 km) to the west of Galita island. The radar of the light cruiser Sheffield detected aircraft at 13.30 at a range of about 50 miles (80 km), and 15 minutes later 10 Savoia-Marchetti SM.79 bombers, operating from a base in southern Sardinia, came into sight flying down the starboard side of the convoy. The four transports were in two columns in line ahead, 1,500 yards (1370 m) apart, Gloucester and Malaya leading the columns with Bonaventure and Southampton as sternmost ships and seven destroyers in the screen ahead. Renown and Ark Royal, screened by Sheffield and five destroyers, were in close support on the convoy’s port quarter. All the ships opened a heavy fire, and Ark Royal's Fairey Fulmar fighters went into action, shooting down two of the attackers. Eight of the Italian aircraft dropped bombs, but hit none of the ships. A later attack by 15 Fiat CR.42 fighter-bombers carrying 220-lb (100-kg) bombs was similarly ineffective.

Reconnaissance by carrierborne aircraft and a flying boat of the Royal Air Force from Malta showed the area 115 miles (185 km) ahead of the convoy to be clear, and at dusk of 9 January, in a position 35 miles (55 km) to the west of the Narrows and after Ark Royal had launched the six Swordfish torpedo bombers to boost the air capabilities of Malta, Force 'H' parted company with the 'Excess' to return to Gibraltar. Escorted by Gloucester, Southampton, Bonaventure and five destroyers, the convoy passed the island of Pantelleria just after the moon had set on 9 January.

At about 07.20 on 10 January, just as dawn was breaking, in a position 14 miles (22.5 km) to the south-east of Pantelleria, the convoy and its escorting warships encountered the Italian torpedo boats Circe and Vega and, unknown to the British, the submarine Ruggiero Settimo. Despite the fact that they were facing an altogether superior strength, all three of the Italians vessels launched torpedoes at the British force, and the two torpedo boats were then engaged first by Bonaventure and later by Southampton and two destroyers. Vega was brought to a stop by gunfire and sunk at 08.30, with the loss of all but two of her crew, by a torpedo launched from Hereward, but Circe managed to escape without suffering any damage. Bonaventure sustained some damage in this engagement, and two of her men were killed, and the light cruisers also expended about three-quarters of their ammunition in the engagement.

Before end of the engagement, which pushed the British convoy somewhat to the south of its planned course, at about 08.00 Cunningham arrived on the scene with Warspite and Valiant, and at 08.30 had just formed the two battleships and Illustrious astern of the convoy when the destroyer Gallant struck a mine at 08.35 and had her bow blown off; 65 men were also killed. Gallant was taken in tow by Mohawk toward Malta, while the cruisers of Force 'B' provided protection from air attacks. The 'Excess' and MW.5½ convoys arrived at Malta and the ME.6 convoy departed the island for Alexandria.

At 09.30, Fulmar fighters from Illustrious intercepted and shot down an Italian aeroplane shadowing Force 'A'. Valiant avoided torpedoes launched by two SM.79 bombers approaching under the radar horizon at 12.30. As the British combat air patrol of Fulmar fighters dropped altitude to engage the SM.79 bombers, Force 'A' was attacked at 12.35 by 18 Heinkel He 111 bombers of Oberst Alexander Holle’s Kampfgeschwader 26 and 43 Junkers Ju 87 dive-bombers of Oberstleutnant Walter Hagen’s Stukageschwader 1 and Oberstleutnant Oskar Dinort’s StG 2 escorted by 10 Messerschmitt Bf 110 heavy fighters of Oberst Johann Schalk’s Zerstörergeschwader 26.

For the first time in the Mediterranean campaign, therefore, German dive-bombers made their presence felt in their seriously damaging attacks on Illustrious. As noted above, Italian high-level bombers and torpedo aircraft also attacked the fleet at the same time or just before this, but were unsuccessful. Now Illustrious was hit five times, mostly with 1,102-lb (500-kg) armour-piercing bombs, and her casualties were 13 officers and 113 men killed, and seven officers and 84 men wounded. Illustrious was the main target of the Axis aircraft, and was soon enveloped in waterspouts and the mist clouds raised by bomb explosions in the water. Some bombers, diving from an altitude of 11,800 ft (3600 m) or so delayed the release of their bombs until reaching a pull-out altitude thought to have been lower than the height of Illustrious's funnel. Just before the attack developed four Fulmar fighters, which had been patrolling above the fleet, chased off some Italian torpedo aircraft some 25 miles (40 km) to the west. While on this chase, at 12.35, a strong force of aircraft was reported by Valiant, on the basis of her radar, to be approaching from the north. The four Fulmar fighters were ordered back, and four fresh aircraft flown off Illustrious, which had to make a 100° turn to starboard into the wind in order that the aircraft could be launched, and the Axis aircraft came into sight in the middle of the operation. The ships opened fire and, just as they had got back to their base course of 110° and were assuming loose formation, the new attack began. Some 20 Ju 87 dive-bombers attacked Illustrious from 12.40, and about 12 attacked the battleships and screening warships. In his subsequent report, the captain of Illustrious pointed out that a force of at least 12 fighters in the air would have been required to make any impression on the Axis attack, and double that number to drive it away.

The Fulmar fighters of the combat air patrol had not returned from chasing the SM.79 bombers which had attacked Valiant, and the four recently launched fighters of the same type were unable to gain altitude rapidly enough to break up the attack. Even so, the British fighters and the warships' anti-aircraft fire claimed seven or eight Axis warplanes shot down during the continuing air attacks on the ships of Force 'A' as the British fighters, which lost only one of their own number, shuttled to airfields on Malta to refuel and rearm.

After this first attack on Illustrious had ended, Cunningham sent the carrier to Malta under escort by two destroyers. She arrived in harbour about 21.00 on the same day, and while on her way had come under other attacks from the air. High-level bombers attacked at 13.40, dive-bombers at 16.10 and lastly, at 19.20, a few torpedo aircraft started to attack, but were driven off by the 'blind' barrage of anti-aircraft fire lofted by the carrier and her escorts.

The appearance of German dive-bombers in the Mediterranean theatre at a time when the British had established an unquestioned superiority over the Italians came to exercise an important influence on future operations. A heavy menace was now loomed over the route with range of Sicilian airfields, and the passage to Malta to become one of considerably greater danger.

Warspite was slightly damaged by a single bomb. Illustrious was struck by five bombs, of which one failed to explode, and a near miss disabled her rudder mechanism. A bomb striking a lowered elevator caused extensive hangar damage, inflicted a large number of casualties among the aircraft maintenance personnel, and destroyed nine Swordfish and five Fulmar aircraft. At 15.30 Illustrious headed for Malta, steering with her engines, even as the bombing continued. Seven SM.79 bombers were driven off by the density of the anti-aircraft fire, but an attack by six Italian Ju 87 dive-bombers at 16.00 scored another bomb hit and two near misses. A force of 14 German Ju 87 dive-bombers missed Valiant and Janus, and a later attack by 14 He 111 bombers was also ineffective. Illustrious reached Malta at 21.30 with 126 dead and 91 wounded.

By the morning of 11 January the three of the 'Excess' convoy’s merchant ships bound for Piraeus and the two of the ME.5½ convoy’s ships bound for Alexandria were in company 115 miles (185 km) to the east of Malta under the close escort of York, Calcutta and two destroyers. The battleships, together with the cruisers Orion and Perth, had kept some 30 miles (50 km) to the north of the convoy during the night of 10/11 January before closing in support on 11 January. At 12.00 on 11 January, Gloucester and Southampton of Renouf’s Force 'B' were in a position about 57.5 miles (92.5 km) astern of the ME.6 convoy, which was being escorted by Orion and Perth. Renouf was now instructed to overtake and support ME.6, but at 15.22 the two cruisers were attacked by 12 German dive-bombers. Neither of the ships was equipped with radar, and it is possible that the ships had relaxed their vigilance in the belief that they had drawn clear of air attacks as they were then some 255 miles (410 km) from Sicily. Both ships were hit,Southampton being severely damaged and set badly on fire. About four hours later Pridham-Wippell arrived in Orion, which sank Southampton with three torpedoes.

At dawn on 11 January, Gallant was beached in Malta’s Grand Harbour, but on subsequent examination was found to be so severely damaged that repair would have been neither feasible nor cost effective. As Mohawk and the cruisers of Force 'B' steamed from Malta to rejoin Force 'A', they were surprised by 12 Ju 87 dive-bombers of the II/StG 2, which dropped down on them out of the sun at 15.20. Gloucester was hit by a bomb which failed to explode, and Southampton was hit by two bombs whose detonations killed 80 men and started fires which could not be extinguished: the ship was abandoned and scuttled some 180 miles (290 km) to the east of Malta. Force 'H' returned to Gibraltar.

On 12 January, to the west of Crete, Force 'A' was reinforced by Force 'B', the cruisers of Force 'D', and the battleship Barham and the fleet carrier Eagle from Alexandria.

On 13 January the ME.6 convoy reached at Alexandria.

What came to be known as the 'Illustrious Blitz' began after the Axis air forces had replenished their bomb stocks, severely depleted during the attacks of 10 and 11 January. The Axis air forces now began a concerted effort to destroy Illustrious before she could be repaired. Illustrious and Essex were hit by an air raid on 16 January, in which 44 Ju 87 dive-bombers were escorted by 10 Macchi C.202, 10 CR.42 and 20 Bf 110 fighters. A useful result of this raid, so far as the Maltese were concerned, was the fact that bombs exploding in Grand Harbour killed numerous fish which were eagerly collected after the raid and eaten by the besieged Maltese. Illustrious was not seriously damaged, but a bomb exploded in Essex's engine room, killing 15 men and wounding 23 more. There was another heavy air raid on 17 January, and Illustrious was again hit by an air raid on 18 January. The carrier was not damaged by the final major attack on 19 January, and departed Malta on 23 January, leaving the Fulmar fighters of No. 806 Squadron to bolster the defence of the island. Illustrious was able to complete additional repairs after reaching Alexandria on 25 January, but restoration of full combat capability necessitated the long passage, though the Suez Canal and via Durban in South Africa, to the east coast of the USA for major shipyard repairs.

No merchant vessels had been lost during 'Excess', but the British had lost one cruiser sunk and one destroyer damaged beyond repair. By 13 January, therefore, the 14 merchant ships and transports had safely reached their various destinations.

The damage to Illustrious and the loss of Southampton persuaded Cunningham to abandon his earlier plan to undertake a raid on Italian shipping in the Adriatic or on the route linking Italy and Libya, and he therefore returned with the main part of the Mediterranean Fleet to Alexandria. Under the command of Rear Admiral H. B. Rawlings, Barham, Eagle and Ajax had joined Cunningham’s force during the morning of 12 January and proceeded on an anti-ship sweep, but bad weather prevented its completion.