'MB8' was a British naval undertaking by Admiral Sir Andrew Cunningham’s Mediterranean Fleet primarily to support the MW.3 convoy from Alexandria to Malta and the ME.3 convoy from Malta to Alexandria (4/13 November 1940).

The operation was notably complex in concept and execution, and involved six British forces totalling two fleet carriers, five battleships, 10 cruisers and 30 destroyers, including much of Vice Admiral Sir James Somerville’s Gibraltar-based Force 'H', to protect four distinct supply convoys. The operation thus comprised several phases: 'Coat', 'Crack', MW.3, ME.3, AN.6 and, as its primary element, 'Judgement' (i). 'Coat' was a reinforcement convoy from the UK to Malta, carrying troops and anti-aircraft guns, and comprised the battleship Barham, the heavy cruiser Berwick, the light cruiser Glasgow and three destroyers. These were covered by the fleet carrier Ark Royal, the light cruiser Sheffield and three more destroyers, all from Force 'H', out to the middle of the Mediterranean’s western basin. The three Force 'H' destroyers then remained with the convoy as the other warships turned back to Gibraltar at a point some 190 miles (305 km) to the west of Sicily.

The MW.3 convoy comprised five ships (6,054-ton Devis, 5,916-ton fleet auxiliary oiler Plumleaf, 3,338-ton Empire Patrol, 1,587-ton Volo and 12,435-ton Waiwera) bound for Malta from Alexandria, plus two ships more providing supplies to the British garrison force at Souda Bay on the north coast of the island of Crete. The convoy was escorted by the light anti-aircraft cruiser Coventry and three destroyers with more distant support afforded by Force 'A' (fleet carrier Illustrious, battleships Warspite, Malaya and Valiant, heavy cruiser York, light cruiser Gloucester and 13 destroyers), which would then rendezvous with Force 'F' from Gibraltar and then detach Illustrious and four destroyers for 'Judgement' (i). The MW.3 convoy’s five ships were loaded with artillery, ammunition and other matériel for Malta, and onto this major undertaking was 'piggybacked' the AN.6 convoy (3,359-ton Adinda, 5,868-ton tanker British Sergeant, 2,931-ton Hannah Moller, 3,477-ton Odysseus and 758-ton Pass of Balmaha) bound for Souda Bay.

The MW.3 convoy departed Alexandria on 4 November, the day after the AN.3 convoy had sailed, and met the other convoy near the Strait of Kásos to the east of Crete. After having navigated just to the north of the island of Crete, part of the convoy turned to the south and Souda Bay while the remaining part continued toward Malta.

On 6 November the main battle force, including the fleet carrier Illustrious, battleships Ramillies, Malaya and Valiant, cruisers Gloucester and York, and several destroyers, departed Alexandria. Two days later the force was mid-way between Crete and Malta, where it joined the MW.3 convoy.

At 12.30 on 8 November, the MW.3 convoy was intercepted by Italian warplanes, which were driven off by the Fairey Fulmar fighters of Illustrious. Another Italian aeroplane was spotted at 15.20, and this too was forced away. At 16.20, seven Savoia-Marchetti SM.79 torpedo bombers came close enough to be intercepted by the fighters from Illustrious, the British fighters claiming two of the Italian attackers before the other five turned away.

At 09.00 on 9 November Ramillies, along with the cruisers and some destroyers, continued toward Malta while the remaining ships remained at a distance. As a result of poor weather, the cruisers were sent to the north of the convoy to provide early warning of any impending Italian naval attack. During this phase, several Italian aircraft were spotted and at 16.04 a Cant Z.506 Airone long-range floatplane was shot down by one of the Fulmar fighters.

The ME.3 convoy comprised four merchant vessels (7,347-ton Clan Ferguson, 10,492-ton Clan Macaulay, 9,816-ton Lanarkshire and 7,406-ton Memnon) sailing in ballast from Malta to Alexandria under escort of the battleship Ramillies, light anti-aircraft cruiser Coventry and two destroyers.

The AN.6 convoy comprised four slow tankers from Egypt to Greece to support of the British expeditionary force in that country, and was escorted only by a slow trawler. On a basically similar course were reinforcements for Souda Bay in Crete, embarked in the light cruisers Ajax and Australian Sydney as Force 'B', while the cruiser Orion (flag of Vice Admiral H. D. Pridham-Wippell’s Force 'C') transported RAF supplies to the port of Piraeus on mainland Greece and inspected Souda Bay, after which it was to be joined by Force 'B'.

It was planned that all three forces would then rejoin to form Force 'X' for an attack on Italian targets in and round the Strait of Otranto on 11/12 November raid.

'Crack' was an attack on the Sardinian port city of Cagliari by aircraft of the fleet carrier Ark Royal on her way to Malta and branching off from 'Coat'.

The 'Judgement' (i) carrierborne air attack on major units of the Italian fleet in Taranto harbour, was under the overall supervision of Admiral Sir Andrew Cunningham, commander-in-chief of the Mediterranean Fleet, and was undertaken by Fairey Swordfish torpedo bombers from the fleet carrier Illustrious, escorted by the battleships Malaya, Ramillies, Valiant and Warspite. This force would meet the heavy cruiser York, light cruiser Gloucester and three destroyers, then escorting the MW.3 convoy, and provide additional cover. The Barham group of 'Coat' was next to be met, with Illustrious, Gloucester, York and Berwick detaching to attack Taranto, coincident with the Force 'X' raid.

The Italians were aware of the sorties from Alexandria and Gibraltar by 7 November, and sent nine submarines to attack the Malta-bound MW.3 convoy, which was detected on 8 November. Italian bombers failed even to locate the 'Judgement' (i) force, and when Force 'H' was detected as it steamed to the west toward Gibraltar on 9 November, the Italians assumed that the MW.3 convoy had also turned back. Italian confusion arose when Barham, Berwick, Glasgow and their destroyers were detected on 10 November off the island of Lemnos in the northern part of the Aegean Sea. The correct deduction, that the ships had detached from the Gibraltar-bound force, was not accompanied by the correct guess that they would join Cunningham’s forces. On the same day Ramillies, Coventry and two destroyers protecting the ME.3 convoy were detected but again the bombers despatched to attack them failed even to locate them.

The ME.3 convoy from Malta to Alexandria on 10/13 November 1940 was, as noted above, the reciprocal of MW.3, with empty ships returning to Egypt, and was protected by the same 'MB8' operation which had protected the MW.3 convoy. The ships of the ME.3 convoy therefore sailed under escort of the warships which had entered Malta with MW.3, namely the battleship Ramillies, the light anti-aircraft cruiser Coventry and the destroyers Decoy and Defender. The monitor Terror and destroyer Vendetta also sailed with them. The convoy comprised the empty British ships from MF.3, which all reached Alexandria on 13 November.

The very complexity of 'MB8', with its various forces and convoys, succeeded in deceiving the Italians into thinking that only normal convoy operations were being made. While Italian reconnaissance was characteristically bad, in the end it was only Illustrious which the Italians had failed to track.