Convoy SC 42 Convoy SC 42 was the 42nd of the numbered series of World War II Slow Convoys of merchant ships from Sydney , Cape Breton Island to Liverpool . SC 42 was attacked over a three night period in September 1941 , losing 16 ships sunk and 4 damaged . This was the worst Allied loss following the attack on convoy SC 7 the previous year . Two attacking U boats were destroyed . Background . Sixty - five ships departed Sydney ( Nova Scotia ) on 30 August 1941 under local escort , bound for Liverpool . The convoy commodore was Rear Admiral WB Mackenzie in " Everleigh " . A week later , they were met just east of the Strait of Belle Isle by the Canadian 24th Escort Group consisting of the Canadian River class destroyer " Skeena " ( Lt Cdr JC Hibbard , senior officer ) with Flower class corvette s " Alberni " , " Kenogami " , and " Orillia " . Corvettes " Chambly " and " Moosejaw " were conducting training exercises in the convoy path at the direction of Commander James D . Prentice , RCN , and were prepared to reinforce the escort as the convoy entered an area where U - boats were known to be waiting . Ranged against them was the " Markgraf " wolf pack , a group of 14 U - boat s in a patrol line southeast of Greenland . Action . Early on 9 September " U - 85 " sighted the convoy near Cape Farewell , Greenland and made an unsuccessful torpedo attack . She then commenced shadowing , while other " Markgraf " boats moved in . The moon rose on the southern side on the convoy that night , and " U - 432 " torpedoed the silhouetted 5229 - ton British freighter " Muneric " . " Muneric " and her cargo of 7000 tons of iron ore sank rapidly with all 63 of her crew . " Kenogami " commenced firing on a surfaced U - boat without benefit of star shell or flashless powder , and quickly lost contact as the crew lost their night - vision in the flash of gunfire . The convoy made two emergency turns over the next half - hour as ships in convoy reported sighting three more surfaced U - boats . Another emergency convoy turn ninety minutes later caught " Skeena " pursuing a contact at speed . While maneuvering to avoid collision , " Skeena " passed a surfaced U - boat on a reciprocal course , being fired upon by ships in convoy so closely that " Skeena " ' s guns could not be depressed to bear . " U - 652 " torpedoed " Baron Pentland " and " Tahchee " during the excitement . The tanker " Tahchee " was towed back to port by " Orillia " but the 3410 - ton British freighter " Baron Pentland " sank with 1512 standards of lumber and two of her crew . Another emergency turn by the convoy brought two hours of suspenseful quiet while " Orillia " aided " Tahchee " and searched for survivors astern of the convoy . Then " U - 432 " torpedoed the 3205 - ton Dutch freighter " Winterswijk " and the 1113 - ton Norwegian freighter " Stargard " . The freighter " Regin " stopped to rescue " Starguard " ' s survivors and opened fire on a surfaced U - boat . While " Skeena " and " Kenogami " searched for U - boats around stricken " Winterswijk " and " Stargard " , " U - 81 " torpedoed the 3252 - ton British freighter " Sally Maersk " , and the convoy made another emergency turn to avoid a surfaced U - boat . " U - 82 " torpedoed the 7465 - ton British CAM ship " Empire Hudson " less than two hours after " Skeena " regained station ahead of the convoy . Daylight on 10 September brought several periscope sightings and emergency turns by the convoy before " U - 85 " torpedoed the 4748 - ton British freighter " Thistleglen " . " Skeena " and " Alberni " counterattacked and damaged " U - 85 " with depth charges . " Thistleglen " sank with 5200 tons of steel , 2400 tons of pig iron , and 3 of her crew . " U - 82 " torpedoed the 7519 - ton British tanker " Bulysses " that evening . " U - 82 " then torpedoed the 3915 - ton British freighter " Gypsum Queen " shortly after the convoy ordered an emergency turn . " Gypsum Queen " sank quickly with 5500 tons of sulfur and ten of her crew . " Bulysses " sank with 9300 tons of gas oil and 4 of her crew . Other ships in convoy rescued the survivors . The corvettes " Chambly " and " Moosejaw " observed the fireworks of these attacks and surprised " U - 501 " while steaming to reinforce the escort . " U - 501 " was first depth - charged by " Chambly " then rammed by " Moose Jaw " as the damaged submarine surfaced . The captain of " U - 501 " jumped from the conning tower to " Moosejaw " ' s deck ; and " Moosejaw " sent a boarding party to enter the submarine . Eleven Germans and one of the Canadian boarding party ( Stoker William Brown ) were lost when " U - 501 " sank . " U - 501 " was the first U - boat sunk by Canadian escorts . Just after midnight on 10 / 11 September " U - 207 " torpedoed the 4924 - ton British freighter " Berury " and the 4815 - ton British freighter " Stonepool " while " Chambly " and " Moose Jaw " were attacking " U - 501 " . Then " U - 432 " torpedoed the 1231 - ton Swedish freighter " Garm " and " U - 82 " torpedoed the 5463 - ton British freighter " Empire Crossbill " and the 1980 - ton Swedish freighter " Scania " two hours later while " Alberni " , " Kenogami " and " Moosejaw " were rescuing survivors of " Berury " and " Stonepool " . " U - 43 " launched torpedoes unsuccessfully , " U - 433 " damaged a 2200 - ton freighter , " U - 202 " sank the crippled " Scania " , and " U - 105 " sank a straggler . On 11 September , the escort was reinforced by the naval trawler " Buttermere " and Flower class corvettes " Wetaskiwin " , " Mimosa " , and " Gladiolus " from convoy HX 147 and by the 2nd Escort Group consisting of the Admiralty type flotilla leader " Douglas " ( Commander WE Banks senior officer ) , the Town class destroyer " Leamington " , the V and W class destroyer " Veteran " and S class destroyer s " Skate " and " Saladin " . " Leamington " and " Veteran " dropped 21 depth charges on the afternoon of 11 September while investigating an RAF Coastal Command aircraft report of a U - boat ahead of the convoy . Postwar analysis indicated their attacks probably destroyed " U - 207 " . Aftermath . With the arrival of these reinforcements further attacks by " Markgraf " were stifled . Though the group continued to shadow , it was unable to mount any further assaults . The arrival on 12 September of the naval trawler " Windermere " and Town class destroyers " St . Croix " from convoy SC 41 and " Columbia " from convoy HX 147 allowed the remaining original escorts " Skeena " , " Alberni " , and " Kenogami " to leave for refuelling . On 13 September destroyers of the 2nd Escort Group departed for refuelling following the arrival of American destroyers " Sims " , " Hughes " and " Russell " . The last incident of the voyage took place three days later when " U - 98 " torpedoed the 4392 - ton British freighter " Jedmore " as the convoy approached North Channel on the late afternoon of 16 September . Convoy SC 42 arrived in Liverpool on 20 September 1941 . Sixteen ships totalling 68 , 259 GRT had been sunk and four ships ( 14 , 132 GRT ) damaged . One ship had turned back . Forty four ships arrived safely and unharmed , and two U - boats had been destroyed , though one of these sinkings was not confirmed until after the war .