'MB' (iv) was the British naval support operation for the MF.2 fast convoy from Alexandria to Malta and MS.2 slow convoy in tandem with the 'Hats' movement of reinforcements for Admiral Sir Andrew Cunningham’s Mediterranean Fleet (30 August/5 September 1940).

As the latter passed through the Strait of Gibraltar and headed to the east in the direction of Alexandria, in a concerted effort to saturate the Italian naval and air capabilities in the central part of the Mediterranean Cunningham departed Alexandria early on 30 August with the battleships Warspite and Malaya, the fleet carrier Eagle, the light cruisers Orion and Australian Sydney, and the destroyers Decoy, Defender, Hereward, Imperial, Australian Stuart, Vampire, Vendetta and Voyager, and Free Polish Garland. This Force 'I' shaped course for a position to the west of Crete. The 3^rd Cruiser Squadron (heavy cruiser Kent and light cruisers Gloucester and Liverpool) and the destroyers Hasty, Hyperion and Ilex had already sailed to make a detour through the Kásos Strait and the southern part of the Aegean Sea, and a supply convoy for Malta consisting of two store ships, the 10,605-ton Cornwall and 1,587-ton Volo, together with the 5,916-ton fleet auxiliary oiler Plumleaf, had departed during the evening of the previous day escorted by four destroyers.

At 12.00 on 31 August the 3^rd Cruiser Squadron joined the battle fleet to the south-west of Cape Matapan. The Italians launched no air attacks on the fleet, but during the afternoon undertook a series of bombing raids on the convoy, and scored one hit aft on Cornwall, putting the ship’s steering gear and radio out of action, destroying both her guns, blasting a hole below the waterline and starting a fire. In spite of the damage, Captain F. C. Pretty steered his ship with the engines, and thus maintained his place in the convoy, which reached Malta without further mishap shortly before 12.00 on 2 September.

Meanwhile, during the evening of 31 August, air reconnaissance and submarine reports indicated that there was an Italian naval force of two battleships, seven cruisers and eight destroyers only 150 miles (240 km) to the north-west and steering a south-easterly course. Cunningham decided to close the convoy, which was some 57.5 miles (92.5 km) to the south, and remain for the night about 25 miles (40 km) to the north-west of it. Hopes of a major encounter with the Italian fleet faded on the following day when air searches failed to locate the Italian warships, and it was not until the evening that a flying boat from Malta finally found the Italian fleet at the entrance to the Gulf of Taranto as it returned to base.

During the afternoon of 1 September the 3^rd Cruiser Squadron proceeded ahead to make contact with the forces coming through the Sicilian Narrows. These forces, having made the passage without incident, were sighted by the main body of the Mediterranean Fleet at 09.00. For the rest of that day the fleet remained to the south of Malta, while the destroyers refuelled and Valiant and the two light anti-aircraft cruisers entered harbour to discharge men as well as naval and RAF stores, 587 tons of army stores, including eight 3.7-in (94-mm) heavy anti-aircraft guns, 10 40-mm Bofors light anti-aircraft guns with 10,000 rounds of ammunition and 16 spare barrels, three predictors, height finders, 10 4.5-in (114-mm) anti-aircraft gun barrels, barrels and 100 Bren light machine guns. Light but unsuccessful bombing attacks were experienced during the day, and five Italian aircraft were believed to have been shot down.

Shortly after 24.00 the whole fleet was steaming away to the east. Cunningham had planned his return route to the north of Crete in order to carry out attacks on Italian targets in the Dodecanese islands group at dawn on 4 September and also to provide cover for a south-bound Aegean Sea convoy. The attacks consisted of air raids on the two airfields in Rhodes and bombardments of targets on Scarpanto island by cruisers and destroyers. All achieved some measure of success, but Italian fighters caused the loss of four Fairey Swordfish bombers. A flotilla of Italian motor torpedo boats attacked ships off Scarpanto, losing one of their number and suffering damage to others before the survivors were driven off.

To the south of Kásos island the fleet was subjected to three air attacks, but all the Italian bombs fell wide. Other air formations were driven off as they approached, and the Mediterranean Fleet’s ships reached Alexandria on 5 September without damage or casualties.