Operation Vigorous ( 1942, "the Battle of mid-June") was a British operation during the Second World War, to escort supply Convoy MW 11 from the eastern Mediterranean to Malta, which took place from 11 to 16 June 1942. Vigorous was part of Operation Julius, a simultaneous operation with Operation Harpoon from Gibraltar and supporting operations. Sub-convoy MW 11c sailed from Port Said (Egypt) on 11 June, to tempt the Italian battlefleet to sail early, use up fuel and be exposed to submarine and air attack.
Convoy MW 11a and Convoy MW 11b sailed next day from Haifa, Port Said and Alexandria; one ship was sent back because of defects. Italian and German (Axis) aircraft attacked Convoy MW 11c on 12 June and a damaged ship was diverted to Tobruk, just east of Gazala. The merchant ships and escorts rendezvoused on 13 June. The British plans were revealed unwittingly to the Axis by the US Military Attaché in Egypt, Colonel Bonner Fellers, who reported to Washington, D.C. in "Black"-coded wireless messages; it was later discovered that the Black Code had been broken by the (Italian military intelligence).
The convoy and escorts sailed through "Bomb Alley" between Crete and Cyrenaica under attack from Axis bombers, dive-bombers, torpedo-bombers, E-boats and submarines and were then threatened by the sailing of the Italian battlefleet from Taranto. The British relied on aircraft and submarines to repel the Italian fleet but only one heavy cruiser was sunk. When the Italian battleships were within the British convoy and escorts turned back while the Italians suffered losses from torpedo-bombers, bombers and submarines but little more damage was inflicted and after several more turns towards and away from Malta, the convoy and escorts returned to Alexandria on 16 June. The Eighth Army lost the Battle of Gazala (26 May – 21 June) and abandoned landing grounds that air cover for Convoy MW 11 came from.
Operation Julius and Operation Vigorous failed, only two merchant ships from Harpoon reaching Malta. Without air cover, the central Mediterranean was closed to the British. Malta could not be revived as an offensive base and the British resorted submarines to deliver aviation fuel. No convoys ran from the eastern Mediterranean until Libya was re-conquered. More Spitfires were delivered to Malta in July and losses reduced the tempo of operations by the and . Offensive operations against Axis convoys to Libya began and Operation Pedestal in August delivered four merchant ships and an oil tanker from Gibraltar, further reviving Malta as an offensive base.
Background
Malta
Siege, 1942
Axis bombing smashed the docks, ships, aircraft and airfields by the end of April 1942 and then the bombing was switched to targets preliminary to invasion: camps, barracks, warehouses and road junctions. After 18 April, German bombing suddenly stopped and Italian bombers took over, regularly bombing with small formations of aircraft. During the month, Axis aircraft flew more than against all but fighter sorties. The British had lost down in combat against losses during the dropping of of bombs, three times the March figure, on the docks, on airfields. The bombing demolished or damaged were killed and wounded; good shelters existed but some casualties were caused by delayed-action bombs. Rations of meat, fats and sugar were cut further and on 5 May, the bread ration was cut to per day, enough to last until late July; pasta rations had already been stopped and there had been a poor winter potato harvest.
Three destroyers, three submarines, three minesweepers, five tugs, a water carrier and a floating crane were sunk in port and more ships damaged. The island continued to function as a staging post but the Axis bombing campaign neutralised Malta as an offensive base. Two boats of the 10th Submarine Flotilla had been sunk, two were damaged in harbour and on 26 April the flotilla was ordered out because of mining by small fast craft, which were undetectable by radar and inaudible during the bombing; the surviving minesweepers were too reduced in numbers to clear the approaches. Three reconnaissance aircraft remained and only sorties were flown, eleven more by FAA aircraft during the month and by the start of June, only two Fairey Albacores and two Fairey Swordfish were left.
Offensive operations
From December 1941, bombing neutralised Malta, British decrypts of Italian cipher messages showed more sailings and fewer losses and on 23 February 1942, an Italian "battleship convoy" reached Tripoli. By the end of February, had crossed without escort and an intelligence blackout caused by a change to the machine in early March made little difference to the British for lack of means. After the British broke again, supply journeys had been made by May, only nine being spotted by air reconnaissance. On 14 April, five Malta aircraft were shot down and the submarine was lost. On 10 March, the cruiser was sunk by a U-boat and on 10 May, three of four destroyers were sunk by the . In February and March, Axis losses were of supplies, those sent in April less than one per cent and May losses were
The Axis was able to reinforce North Africa sufficient for Rommel to try to attack before the British. In late April, the British Chiefs of Staff ruled that there would be no convoy to Malta in May, because the Italian fleet could be expected to sail and the convoy would need battleship and aircraft carrier cover, which was not available. An operation to fly Spitfires to Malta succeeded and anti-aircraft ammunition was to be supplied by fast minelayer, with which Malta would have to hold on until mid-June, when the situation in the Western Desert might be clearer. Should Martuba or Benghazi in Cyrenaica be captured by the Eighth Army, a westbound convoy from Alexandria might survive without cover from battleships and aircraft carriers. It would also be known if aircraft had been diverted to the Russian Front and if the crisis in the Indian Ocean had abated, sufficient for ships to escort a fast convoy from Alexandria.
Operation Hercules () was an Axis plan to invade Malta and during 1942, reinforcement of the in Sicily and the bombing campaign against the island led to speculation that it was the prelude to invasion. Gleanings from prisoners of war and diplomatic sources led to a certain apprehension about the meaning of troop movements in southern Italy. The absence of evidence from signals intelligence and air reconnaissance led to a conclusion that an invasion was not imminent but the need to protect the source of information meant that this was not disclosed by the British. That preparations were being made was revealed on 7 February through the decryption of Enigma messages but by 23 March the scare died down and more bombing was expected. By 31 March the progress of the Axis bombing campaign led to a prediction that the attempt would be made in April but this was soon discounted.
Although the bombing offensive increased from in February, to in March, in April, Enigma decodes showed that there were still aircraft in Sicily, not the originally intended, because aircraft were detained in Russia by the Soviet winter offensive and on 26 April, Enigma revealed that II was being withdrawn. By 2 May, a bomber group and a fighter group had been withdrawn with more to follow, which explained the lull. Hitler was lukewarm about the operation, in case the Italian navy left down German airborne forces but the capture of Tobruk in mid-June made it appear that the invasion was unnecessary. Hitler and Mussolini agreed to pursuing the British into Egypt for the rest of June and into July, which meant cancelling Hercules.
Western Desert Campaign
After the success of Operation Crusader (18 November – 30 December 1941), the Eighth Army advanced west to El Agheila in Libya, capturing airfields and landing grounds useful for air cover for Malta convoys. The British misjudged the speed of Axis reinforcement and expected to attack well before the Axis but forestalled the Eighth Army by beginning an offensive on 21 January 1942.
By 6 February, the British had been defeated, forced to retreat east of the Jebel Akhdar back to the Gazala line. The new front line was just west of Tobruk, where had begun its retirement seven weeks earlier. At the Battle of Gazala (26 May – 21 June), attacked first again but appeared close to defeat until 11 June. Operation Julius began on the same day as the broke out and by 14 June, forced the British to retreat towards Tobruk. The Axis then forces pursued the British into Egypt and the Desert Air Force lost the Libyan landing grounds from which to cover Malta convoys.
Prelude
Operation Julius
Two weeks before the convoys, the carrier began operations to deliver 63 Spitfires to Malta, which increased the number to fighters. Air operations for the two convoys began on 24 May, when Vickers Wellington bombers of 104 Squadron from Malta, began bombing airfields and ports in Sicily and southern Italy. On 11 June, the Wellingtons were withdrawn to accommodate six Wellington torpedo bombers of 38 Squadron, Bristol Beaufort torpedo-bombers of 217 Squadron and Martin Baltimore reconnaissance aircraft of 69 Squadron. Aircraft from Gibraltar, Malta and Egypt also began reconnaissance flights on 11 June, searching for the Italian fleet.
Twelve Beauforts of 39 Squadron at Bir Amud in Egypt, five B-24 Liberator bombers of 160 Squadron and about of the Halverson Detachment United States Army Air Forces (USAAF) at RAF Fayid, were also made available. Short-range fighters based in Palestine, Egypt, Cyrenaica and Malta, were to provide air cover at first and as the convoy moved out of range, protection would be taken over by Kittyhawks of 250 Squadron with long-range fuel tanks, Beaufighters from 252 Squadron and 272 Squadron and Beaufighter night fighters from 227 Squadron. Air cover from Cyrenaica could not overlap with coverage from Malta leaving a gap but Wellingtons of 205 Group and the light bombers of the Desert Air Force would attack Axis airfields in North Africa. The coastal 201 Group would provide reconnaissance and anti-submarine sorties and a small sabotage party was to land on Crete to attack Axis aircraft on the ground.
Operation Vigorous
Vigorous was planned as a joint Royal Navy–RAF operation, to be conducted from the headquarters of 201 Naval Co-operation Group by Admiral Henry Harwood and Air Marshal Arthur Tedder, with Rear Admiral Philip Vian in command of the convoy and escorts (Force A). On 22 March 1942, in Operation MG 1 protecting Convoy MW 10 to Malta, the Second Battle of Sirte between the Italian fleet and the British escorts had been fought. The British escorts had held off the Italian fleet for hours but in the longer days of June, it was doubted that the feat could be repeated. If a larger Italian force attacked the convoy, Vian was to protect the convoy with smoke and the escorts were to repulse the attackers with torpedoes and try to inflict early casualties using gunfire against two of the Italian ships. The success of the convoy would depend on the Italian fleet being damaged by air and submarine attack before it could close on the ships, rather than on surface action because the battleships and were still out of action.