Convoy SC 107 Convoy SC 107 was the 107th of the numbered series of World War II Slow Convoys of merchant ships from Sydney , Cape Breton Island to Liverpool . The ships departed New York City on 24 October 1942 and were found and engaged by a wolfpack of U - boat s which sank fifteen ships . It was the heaviest loss of ships from any trans - Atlantic convoy through the winter of 1942 - 43 . Background . As western Atlantic coastal convoys brought an end to the " Second Happy Time " , Admiral Karl Dönitz , the " Befehlshaber der U - Boote " ( " BdU " ) or commander in chief of U - Boats , shifted focus to the mid - Atlantic to avoid aircraft patrols . Although convoy routing was less predictable in the mid - ocean , Dönitz anticipated that the increased numbers of U - boats being produced would be able to effectively search for convoys with the advantage of intelligence gained through " B - Dienst " decryption of British Naval Cypher Number 3 . However , only 20 percent of the 180 trans - Atlantic convoys sailing from the end of July 1942 until the end of April 1943 lost ships to U - boat attack . Discovery . Convoy SC 107 was found and reported by " U - 522 " on 29 October as the Western Local Escort Force turned the convoy over to Mid - Ocean Escort Force Group C - 4 consisting of the Canadian River class destroyer " Restigouche " with the Flower class corvette s " Amherst " , " Arvida " , " Sherbrooke " , " Celandine " , " Algoma " , " Moose Jaw " , and the Convoy rescue ship " Stockport " . As wolfpack " Veilchen " assembled to intercept the convoy , " U - 520 " was sunk by a No . 10 Squadron RCAF Digby bomber , and " U - 658 " was sunk by a RCAF Lockheed Hudson . First attack on 1 / 2 November . " Stockport " and " Restigouche " located 25 HF / DF transmissions on the afternoon of 1 November , but the single destroyer was unable to investigate all of them . While " Arvida " had a RADAR malfunction , U - boat Ace " Kapitänleutnant " Siegfried von Forstner ' s " U - 402 " penetrated the starboard side on the convoy screen about midnight to torpedo the British freighter " Empire Sunrise " . " Restigouche " narrowly avoided torpedoes launched a short time later by " U - 381 " . While " Celandine " dropped astern to screen " Stockport " rescuing survivors from " Empire Sunrise " , " U - 402 " twice more penetrated the convoy screen where " Celadine " had been and torpedoed the Greek freighter " Rinos " and British freighters " Dalcroy " , , and " Empire Leopard " . " U - 522 " torpedoed the Greek freighter " Mount Pelion " and British freighters " Hartington " and " Maratima " . " Kapitänleutnant " von Forstner would receive the Knight ' s Cross of the Iron Cross for his work in " U - 402 " during this convoy and in Convoy SC - 118 on the next patrol . 2 November . Stormy weather caused the U - boats to lose contact after " U - 522 " torpedoed Greek freighter " Parthenon " in a daylight attack . The escort was reinforced by the V class destroyer " Vanessa " from convoy HX - 213 before nine U - boats regained contact when visibility improved on 3 November . Second attack on 3 / 4 November . " U - 521 " torpedoed the American tanker " Hahira " in a daylight attack on 3 November . " U - 89 " torpedoed the convoy commodore ' s freighter " Jeypore " after sunset on 3 November while " U - 132 " torpedoed the Dutch freighter and British freighters " Empire Lynx " and " Hatimura " . " U - 132 " is believed to have been destroyed by the detonation of the ammunition cargo of the latter ship . On 4 November , " Arvida " and " Celandine " were detached to Iceland with " Stockport " and two tugs overcrowded with 240 survivors . " U - 89 " torpedoed the British freighter " Daleby " shortly before the convoy escort was reinforced by the USCG Treasury Class Cutter " Ingham " and the Wickes class destroyer s " Leary " and " Schenck " from Iceland . No . 120 Squadron RAF B - 24 Liberator s scrambled from Iceland drove off the remaining U - boats , and the convoy reached Liverpool on 10 November .