Convoy SL 125 Convoy SL 125 was the 125th of the numbered series of World War II 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 . Initial contact . German cryptographers decoded message traffic containing tactical information about convoy SL 125 , and wolf pack " Streitaxt " ( battle axe ) , consisting of " U - 103 " , " U - 134 " , " U - 203 " , " U - 409 " , " U - 440 " , " U - 509 " , " U - 510 " , " U - 572 " , " U - 604 " , and " U - 659 " was assembled 23 October to intercept the convoy west of the Canary Islands . The only United States merchant ship and escorting sloop HMS " Bridgewater " , Isles class trawler HMS " Copinsay " and Free French corvette " Commandant Drogou " had been detached by the time " U - 203 " found the convoy on 25 October . U - 203 was depth charged and damaged while attempting to attack the straggling British tanker " Anglo Maersk " . The tanker was subsequently shadowed by " U - 134 " and damaged by " U - 509 " . 27 October . The armed merchant cruiser and troopship HMS " Esperance Bay " was detached with the Shakespearian class trawler HMS " Juliet " , tugboat HMS " Salvonia " , and repair ship HMNZS " Kelantan " when " U - 409 " found and reported the main convoy of 37 ships on 27 October . Forty - one merchant ships were left in the care of Flower class corvette s " Petunia " , " Cowslip " , " Crocus " , and " Woodruff " . " U - 659 " was depth charged and damaged while attempting to attack the convoy . After moonrise , " U - 604 " sank the damaged " Anglo Maersk " while " U - 509 " torpedoed the British freighters " Pacific Star " and " Stentor " . 28 October . After unsuccessful submerged daylight attacks on 28 October , " U - 509 " sank the British freighter " Nagpore " and damaged the British freighter " Hopecastle " after sunset . " U - 203 " sank the damaged " Hopecastle " before dawn . 29 October . " U - 509 " sank the British freighter " Britanny " during foul weather on the night of 29 – 30 October . The British tanker " Bullmouth " ( sailing in ballast ) was damaged by " U - 409 " and sunk by " U - 659 " . The British freighter " Corinaldo " was damaged by both " U - 509 " and " U - 659 " before being sunk by " U - 203 " . 30 October . Improved weather brought coordinated attacks on the night of 30 – 31 October . " U - 409 " torpedoed the British freighter " Silverwillow " while " U - 604 " torpedoed the British transport " President Doumer " and the British freighter " Baron Vernon " . The British freighter " Tasmania " was damaged by " U - 659 " and sunk by " U - 103 " . The Norwegian freighter " Alaska " was damaged by " U - 510 " , but reached England safely with the help of newly arriving escorts . Aftermath . Long range bombers of RAF Coastal Command arrived over the convoy on 31 October . Admiral Dönitz cancelled operations on the morning of 1 November . The convoy was reinforced with eleven more escorts and reached Liverpool on 9 November . It had suffered the greatest loss of any SL convoy , but its timing focused the available U - boat s in the area away from the Operation Torch convoys for the allied invasion of North Africa on 8 November 1942 . Some historians have suggested that the trade convoy SL 125 was an intentional tactical diversion to keep U - boats away from the loaded troop transports . Eleven of the ships surviving this convoy sailed two months later with convoy ON 154 , in which four of them were sunk .