'Vigorous' (ii) was a British naval undertaking by Admiral Sir Henry Harwood’s Mediterranean Fleet to ensure the passage of the MW.11 westbound supply convoy to Malta (11/16 June 1942).

The operation was undertaken at the same time as the 'Harpoon' (ii) eastbound convoy from Gibraltar, the object being to split the attentions and offensive capabilities of the Axis air and sea opposition so that the convoys stood a better chance of reaching the beleaguered island on successive days with vitally needed supplies.

While 'Harpoon' (ii) comprised six merchant ships, 'Vigorous' (ii) had at its core 11 ships (8,049-ton British freighter City of Pretoria, 8,063-ton British freighter City of Calcutta, 6,104-ton British freighter Bhutan, 5,410-ton British tanker Potaro, 8,071-ton US tanker Bulkoil, 8,126-ton Dutch freighter Rembrandt, 6,811-ton Dutch freighter Aagtekerk, 8,036-ton British freighter City of Edinburgh, 8,039-ton British freighter City of Lincoln, 5,450-ton Norwegian freighter Elisabeth Bakke and 7,540-ton British freighter Ajax) escorted by the several groups of warships led by Rear Admiral Sir Philip Vian, commanding the 15^th Cruiser Squadron. The close escort comprised the destroyers Fortune, Griffin and Hotspur of the 2^nd Destroyer Flotilla, the escort destroyers Dulverton, Exmoor, Croome, Eridge, Airedale, Beaufort, Hurworth, Tetcott and Aldenham of the 5^th Destroyer Flotilla, the corvettes Delphinium, Primula, Erica and Snapdragon, the minesweepers Boston and Seaham, and the old battleship Centurion as an air attack decoy; there were also the rescue ships Antwerp and Malines.

More distant cover was provided by the 15^th Cruiser Squadron with the light anti-aircraft cruisers Cleopatra, Dido, Euryalus and Hermione, the 4^th Cruiser Squadron with the light cruisers Arethusa, Birmingham and Newcastle), and 14 destroyers (7^th Destroyer Flotilla with Napier, Nestor and Australian Nizam and Norman, 14^th Destroyer Flotilla with Jervis, Kelvin and Javelin, 12^th Destroyer Flotilla with Pakenham, Paladin and Inconstant, and 22^nd Destroyer Flotilla with Sikh, Zulu, Hasty and Hero).

Four of the freighters towed motor torpedo boats for short-range torpedo attacks on any Italian warships which attempted to intervene, but the motor torpedo boats had to turn back to Alexandria because of stormy weather, MTB-259 sinking before it reached port. The British submarines Proteus, Thorn, Taku, Thrasher, Porpoise, Una, P31, P34 and P35 were patrolling off Taranto and south of the Strait of Messina, while P42, P43, P46 and P211 were operating between Sicily and Sardinia.

Four of the cruisers and 10 of the destroyers were 'on loan' to the Mediterranean Fleet from the Eastern Fleet for this operation. All too evident, however, were the lack of any heavy ships to deal with any Italian battle fleet interception or of any aircraft carriers to deal with Axis reconnaissance or attack aircraft. The old battleship Centurion, now used mainly as a radio-controlled target and fitted only with anti-aircraft weapons, was allocated in the hope that the Axis forces would be deceived into thinking that there was a fully armed battleship among the escort force, but greater reliance was placed on the substantial force of attack aircraft and submarines provided for 'Vigorous' (ii). These should have been more than adequate for the task, but the British lacked reconnaissance aircraft and these attack forces were thus denied the accurate intelligence which would have enabled them to operate effectively against the Italian surface forces.

Harwood and Air Chief Marshal Sir Arthur Tedder, the air commander, personally supervised the operation from the headquarters of Air Vice Marshal L. H. Slatter’s No. 201 Group naval co-operation element.
The 'Vigorous' (ii) operation got under way on 11 June with the sailing from Port Said of the MW.11C diversionary group (the merchantmen Aagtekirk, Bhutan, City of Calcutta and Rembrandt, cruiser Coventry and eight destroyers) in 'Rembrandt' intended to proceed as far to the east as Tobruk before turning back to meet the main convoy. The British hoped that the Italian naval forces would be decoyed toward the south by the diversionary group, then fail to find it and have to turn back for lack of fuel, so leaving the main convoy the chance to make good progress without Axis interference.

The main convoy assembled in two parts (MW.11B at Alexandria with the tankers Bulkoil and Potaro escorted by the destroyers Fortune, Pakenham and Paladin, and MW.11A at Haifa with the merchant vessels Ajax, City of Edinburgh, City of Lincoln, City of Pretoria and Elizabeth Bakke escorted by the destroyers Hotspur, Inconstant, Napier, Nestor, Nizam and Norman) and joined the diversionary convoy off Alexandria on 13 June, the whole convoy then moving east to be joined off Tobruk by Vian’s escort of seven cruisers and 17 destroyers.

The escorting forces were the cruisers Arethusa, Birmingham, Cleopatra, Dido, Euryalus, Hermione and Newcastle, escort destroyers Hurworth and Tetcott of the AA-capable 'Hunt' class, and the fleet destroyers Griffin, Hasty, Hero, Javelin, Jervis, Kelvin, Sikh and Zulu, few of which had any great AA capability. Additionally there sailed the corvettes Delphinium, Erica, Primula and Snapdragon and minesweepers Boston and Seaham. The miscellaneous collection was completed by four motor torpedo boats, the rescue ships Antwerp and Malines, and the essentially disarmed battleship Centurion. The rationale for the inclusion of the last was that she was crudely disguised as a unit of the 'King George V' class, her pre-World War I armour might afford her a better chance of survival than a merchant ship, carried 2,000 tons of supplies, and was both available and expendable. The combined convoy was intended for a mean speed of 13 kt, an overly optimistic estimate as became clear quite early in the operation.

The MW.11C convoy sailed ahead of the other two sections, on 11 June and as ordered proceeded as far to the west as Tobruk before turning back to join the other two sections. The plan was that this sortie, ostensibly to supply Tobruk, would lure the Italian fleet out of its bases, expose it to attack and cause it to use its fuel supplies, but the ruse did not succeed. Escorted by the anti-aircraft cruiser Coventry and escort destroyers Airedale, Aldenham, Beaufort, Croome, Dulverton, Eridge and Hurworth, which were joined off Alexandria by Exmoor, the convoy had just turned to return to the rendezvous on the evening of 12 June when it was attacked by dive-bombers. City of Calcutta was damaged and had to be detached to Tobruk with Croome and Exmoor. The remaining ships returned east and rendezvoused with the balance of the convoy on 13 June, when the escort destroyers were sent back to Alexandria to fuel. Of the remainder of the convoy, Elizabeth Bakke proved too slow and was ordered back to Alexandria, so it was only nine ships and Centurion which moved on toward Malta.

Axis aircraft kept track of the convoy through the night of 13/14 June, and heavy attacks were launched during 14 June despite the attentions of British land-based fighters. During the night of 13 June the escort was also depleted as the weather proved too rough for the motor torpedo boats, which were now ordered to return, and the boats reached Alexandria on 14 June without MTB-259, which had foundered. The corvette Erica also developed defects and left the convoy, while Aagtekirk proved too slow and was sent in to Tobruk, escorted by Tetcott and Primula, on 14 June. Aagtekirk was attacked by 40 German dive-bombers and sank off the port.

Farther out to sea, the main escort joined the convoy, and the two destroyers which had taken in City of Calcutta rejoined the convoy’s escort. During the afternoon of 14 June an air attack sank Bhutan and damaged Potaro, which was nonetheless able to continue with the convoy. The two rescue ships picked up Bhutan's survivors and then headed for Tobruk. A submarine-fired torpedo almost hit Pakenham, and from a time shortly after sunset Italian torpedo craft tracked the convoy before attacking at midnight but being driven off.

By this time a sizeable Italian force was well out to sea: commanded by Ammiraglio di Armata Angelo Iachino, this force comprised the modern battleships Vittorio Veneto and Littorio of the 9a Divisione Navi di Battaglia, the heavy cruisers Gorizia and Trento, the light cruisers Giuseppe Garibaldi and Luigi di Savoia Duca d’Aosta, and the destroyers Legionario, Folgore, Freccia and Saetta of the 7a Divisione Cacciatorpediniere, Alpino, Bersagliere, Antonio Pigafetta and Mitragliere of the 13a Divisione Cacciatorpediniere, and Aviere, Geniere, Camicia Nera and Corazziere of the 11a Divisione Cacciatorpediniere, which had departed Taranto and could thus be in the position to intercept the convoy from about 07.00 on 15 June.

Aware from reconnaissance reports that a meeting with the Italian fleet was likely at dawn, Vian appreciated that he stood no chance of repeating the action of Sirte over a period of 14 hours in good weather, and turned to the east at 01.45 to delay the interception. During the turn Newcastle and other ships became separated from the convoy and in a subsequent Italian torpedo craft attack Newcastle was damaged and the destroyer Hasty was sunk by a torpedo from S.55.

At dawn the Italian fleet was some 200 miles (320 km) to the north of the convoy, and Vian was once again ordered to make for Malta while Allied aircraft struck at the Italians. The first blood was drawn by Malta-based aircraft, which torpedoed and crippled the heavy cruiser Trento, which was later sunk by the submarine Umbra. The British submarines were meanwhile struggling to intercept the Italians, and an Egypt-launched air raid developed between 09.00 and 10.00, scoring single bomb and torpedo hits on Littorio.

Virtual chaos now ensued in the British camp, for at 09.40 Harwood ordered Vian to turn back once again then, at 12.00 after hearing the optimistic air reports of damage to the Italian squadron, told Vian to make once more for Malta, and finally at 12.45, having heard that the air reports were too hopeful and that air reconnaissance had lost touch with the Italian squadron, left the matter to the discretion of Vian, who received this signal only at 14.20 after the light cruiser Birmingham had been badly damaged in an air attack, which put part of her armament out of action, and the destroyer Airedale crippled. The destroyer had to be sunk by the surviving British forces, so only a much reduced escort was available for the convoy of six merchantmen, another having been sent back as a straggler. Nestor was hit, taken in tow by Javelin and, with Beaufort and Eridge as a screen, set off toward Alexandria.

Harwood then received firm information that the Italian fleet was retiring and accordingly ordered the convoy to turn once again for Malta. Unfortunately, the order was received at the peak of a heavy air attacks, and it was nearly 19.00 before the situation could be assessed and fuel and ammunition reserves ascertained. With Nestor damaged in the latest raid, fuel in the destroyers low, and less than 30% of ammunition remaining, it was clear that to press on to Malta was impossible. Harwood concurred at 19.39, and the whole convoy started to head back toward Alexandria. During the night the light anti-aircraft cruiser Hermione was hit by a torpedo from Kapitänleutnant Franz-Georg Reschke’s U-205 and sank, the damaged Nestor had also to be sunk, and the bedraggled convoy and escort returned to Alexandria and Port Said on the evening of 17 June. Ajax and Bulkoil were escorted to Port Said by Fortune, Griffin, Inconstant and Pakenham, and the other merchant ships entered Alexandria. Centurion, damaged and with a deep draught, had to anchor outside the Great Pass.

The British had lost one cruiser, three destroyers and two merchantmen, and 'Vigorous' (ii) can be regarded only as a severe tactical defeat for the British. So ended the British attempts to supply Malta by convoy from the east until such time as the British 8^th Army had succeeded in clearing the Axis forces from North Africa, and so provided the RAF with the bases from which it could provide air cover during convoys' passages through the eastern Mediterranean, hitherto dominated by Axis warplanes operating from Crete and the other occupied Greek islands.