Operation Vigorous

Operation Vigorous was a British operation during the Second World War, to escort supply convoy MW11 from the eastern Mediterranean to Malta, which took place from 11–16 June 1942. Vigorous was part of Operation Julius, a simultaneous operation with Operation Harpoon from Gibraltar and supporting operations. Sub-convoy MW11c sailed from Port Said on 11 June, to tempt the Italian battlefleet to sail early, use up fuel and be exposed to submarine and air attack. MW11a and MW11b sailed next day from Haifa, Port Said and Alexandria, one ship being sent back because of defects. Italian and German aircraft attacked MW11c 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 coded wireless messages. The Black Code was later revealed by Ultra to have been broken by the Servizio Informazioni Militare .

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 an Italian battlefleet from Taranto. The British relied on aircraft and submarines to repel the Italian fleet in the absence of battleships and aircraft carriers but only one heavy cruiser was sunk. When the Italian battleships were within 150 nmi the British convoy and escorts were ordered to turn back and wait for the Italians to suffer 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 Battle of Gazala was being fought in Libya during Operation Julius and beginning on 14 June, the British defeat forced the Eighth Army to withdraw eastwards, losing landing grounds from which aircraft could provide air cover for MW11.

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