Operation Vigorous

Operation Vigorous ( Italian: Battaglia di mezzo giugno 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 Servizio Informazioni Militare (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 flee but only one heavy cruiser was sunk. When the Italian battleships were within 150 nmi (170 mi; 280 km) 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 Luftwaffe and Regia Aeronautica. 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.