SL convoys were a numbered series of North Atlantic trade convoys during the Second World War. Merchant ships carrying commodities bound to the British Isles from South America, Africa, and the Indian Ocean traveled independently to Freetown, Sierra Leone to be convoyed for the last leg of their voyage to Liverpool.
On the basis of World War I experience, SL convoys were one of four trade convoy routes organized at the beginning of the Battle of the Atlantic. The other routes were HX convoys from North America, HG convoys from the Mediterranean, and a short-lived series of HN convoys from Norway. Eight ships sailed as convoy SL 1 on 14 September 1939 and three faster ships sailed six days later as a faster section -- sometimes designated SL(F) 1 or SL 1(F). The slower convoy was sometimes similarly suffixed with an (S). Early convoys were usually accompanied by an armed merchant cruiser or one of the South Atlantic Station cruisers based at Freetown; but no anti-submarine screen was provided until the slower and faster sections rendezvoused with a single Escort Group in the Southwest Approaches. [1]
Freetown was little more than a protected anchorage with no shore facilities. The town had been established as a resettlement area for freed slaves, with negligible European development. Convoy operations were coordinated by a naval staff aboard the elderly Union-Castle Liner Edinburgh Castle.Edinburgh Castle and a hospital ship anchored as far offshore as practicable to avoid the unhealthy conditions ashore. Tropical diseases were endemic in the oppressive heat and humidity. Local fresh water supplies were polluted. Refueling coal from the United Kingdom and oil from the West Indies was held and distributed afloat in detained merchant ships. Shore facilities were inadequate to support anti-submarine escorts for convoys until January 1941. [2] Air cover was flown from Cornwall, Gibraltar, and Freetown when conditions allowed; but a northern Azores air gap and a southern Canaries air gap remained where U-boats and surface raiders could patrol the convoy routes unobserved. [3] The northern gap was closed when air patrols began flying from the Azores in October 1943. [4]
Convoy SL 125 sailed on 16 October 1942 before Operation Torch discontinued sailings from Freetown. Shipping was routed along the east coast of the Americas to Halifax until convoy SL 126 sailed from Freetown on 12 March 1943. Convoy SL 128 merged with convoy MKS 12 off Gibraltar in April 1943 to be designated SL 128/MKS 12 and all subsequent SL convoys had a similar joint designation format. The effective range of U-boats was decreased by Allied capture of French Atlantic seaports in 1944. The reduced threat of submarine attack off the African Atlantic coast allowed merchant ships to sail independently to Gibraltar after convoy SL 178/MKS 69 left Freetown on 25 November 1944. [2]
From 7 September 1939, OutBound OB convoys had sailed from Liverpool south through St George's Channel to the open Atlantic. OB convoys were escorted for about four days from Land's End before the convoy would disperse and individual ships proceed independently to their destinations. As U-boats found and sank increasing numbers of ships dispersed from OB convoys, OB convoys were replaced by ON convoys and by OS convoys formed of ships Outbound to the South Atlantic and escorted all the way to Freetown. Convoy OS 1 sailed from Liverpool on 24 July 1941, and reached Freetown on 10 August. An escort group would screen a southbound OS convoy and return with a northbound SL convoy. Convoy OS 40 reached Freetown on 27 September 1942, but following convoys OS 41 and OS 42 dispersed at sea; and OS convoys were suspended by Operation Torch until convoy OS 43 left Liverpool on 14 February 1943. Convoy OS 46 was combined with convoy KMS 13 of ships detaching off Gibraltar with the joint designation OS 46/MKS 13. Sailings from Liverpool continued under the joint designations until convoy OS 130/KMS 105 on 27 May 1945; but, as the Mediterranean route became safe for Indian Ocean destinations, convoy OS 92/KMS 66 was the last to proceed as far as Freetown on 4 November 1944. [5]
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Convoy SL 125 was the 125th of the numbered series of World War II SL convoys of merchant ships from Sierra Leone to Liverpool. Ships carrying commodities bound to the British Isles from South America, Africa, and the Indian Ocean travelled independently to Freetown, Sierra Leone, to be convoyed for the last leg of their voyage. Thirty-seven merchant ships departed Freetown on 16 October 1942 and were joined at sea by five more.
SS Hilary was a British steam passenger liner that was built in 1931 and scrapped in 1959. She spent much of her career on a scheduled service between Liverpool in England and Manaus in Brazil.
Convoys SL 138/MKS 28 were two Allied convoys which ran during the Battle of the Atlantic in World War II. SL 138 was one of the SL convoys from the South Atlantic to Britain, and MKS 28 one of the MKS convoys between Britain and the Mediterranean. They were sailing together on the Gibraltar homeward route, having made a rendezvous off Gibraltar in order to cross the Bay of Biscay with the maximum possible escort. They were the subject of a major U-boat attack in October 1943, the first battle in the Kriegsmarine's renewed Autumn offensive.
Convoys SL 139/MKS 30 were two Allied convoys which ran during the Battle of the Atlantic in World War II. SL 139 was one of the SL convoys from the South Atlantic to Britain, and MKS 30 one of the MKS convoys between Britain and the Mediterranean. They were sailing together on the Gibraltar homeward route, having made a rendezvous off Gibraltar in November 1943. They were the subject of a major U-boat attack, as part of the Kriegsmarine's renewed Autumn offensive.
Convoys SL 140/MKS 31 was a combined Allied convoy which ran during the Battle of the Atlantic in World War II, sailing to Britain in November 1943. SL convoys originated in Freetown, Sierra Leone, with their destination Liverpool and other ports in Britain. This was the 140th convoy to make that trip in WWII. SL 140 was composed of merchant ships bringing raw materials to the UK from various parts of the world. MKS was the designation for convoys from the Mediterranean to Britain. MK indicated ‘Mediterranean to the UK'. More than 100 MK convoys operated during the war. The S in this acronym specified ‘slow.’ This was a slow convoy, since it included thirteen LSTs, which had a top speed of about 10 knots. The LSTs and the additional landing craft they carried would be vital for the upcoming invasion of northern France.
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