SC 48 was a North Atlantic convoy of the SC series which ran during the battle of the Atlantic in World War II.
It was notable for being the occasion of the Kearny incident, which brought the United States one step closer to war with Germany.
Prelude
SC 48 was an east-bound convoy of 52 ships, carrying war materials and sailed from Sydney, Cape Breton on 5 October 1941 bound for Liverpool. It was under the command of Commodore HM Sanders in the MV Castalia.
It was escorted by a Canadian escort group consisting of the (Lt Cdr SW Davis as Senior Officer Escort), and seven s; , , , , , and the Free French Naval Forces' Mimosa.
On 9 October the group Mordbrenner was formed in the area south of Iceland near the Mid-Ocean Meeting Point. This was the point at which North Atlantic convoys were handed over between the Ocean and the Western Approaches escorts at this stage of the Atlantic campaign. Initially the group was composed of four boats : , , and . The next day , and were also ordered to join the group. In addition the following boats sailing from France were sent as reinforcement : , , , , and .
Allied intelligence became aware of the presence of Mordbrenner, and started to divert the convoys then at sea, but a loss of Ultra intelligence on 12/13 October left SC 48 in the dark; and on the night of 14/15 October it was sighted by U-553 (K/L Karl Thurmann).
At this point in time SC 48 was in some disarray; 11 of its ships, including Castalia, were straggling following heavy weather on the night of 9/10 October. Columbia and two of the corvettes, Camrose and Rosthern, were detached looking for them. A third corvette, Shediac was also separated by the storm and out of radio contact. On 14 October SC 48's escort comprised just four corvettes; Wetaskiwin (as Acting SOE), Baddeck, Gladiolus and Mimosa.
Action
15 October 1941
In the early hours of 15 October Thurmann of U-553 reported his contact to U-boat Command (BdU) and was ordered to shadow, whilst other U-boats were gathered for the attack. However Thurmann chose to attack that night, and succeeded in sinking two ships, Silvercedar, which lost 21 crew, and Ila, most of whose crew were saved. U-553 was sighted by Silverhelm, the next ship in the column, which attempted to ram, but failed; U-553 was also sighted by WC Teagle, but she was unable to bring her gun to bear before U-553 escaped.
On 15 October Enigma was re-acquired and Western Approaches Command realized a major attack was building; a number of escorts from nearby convoys were diverted to reinforce SC 48. First a force of US destroyers (DesRon 13), detached from ON 24; two Royal Navy destroyers ( and HMS Broadwater) from TC 14; two Royal Navy corvettes ( and ) from ON 25; and a RCN corvette () from Iceland.
Later on 15 October Columbia rejoined, while U-553 was joined by two more boats; U-558 and U-568. As U-553 continued to shadow, she was sighted by Columbia, who attacked her, driving her away, but with no damage; U-553 fired a torpedo at Columbia, which missed. During the day U-558 joined, having encountered the ship Vancouver Island sailing independently ; she was sunk with the loss of all 73 crew and 32 passengers. Before nightfall U-568 also arrived, and the three boats prepared to attack.
As darkness fell on the night of 15/16 October the U-boats attacked again. U-568 attacked and sank Empire Heron, Gladiolus counter-attacked, and U-568 was driven off. Gladiolus then detached to pick up survivors, but never rejoined the convoy; she was lost with all hands, reportedly sunk by U-568 on the 17th, but more probably much earlier.
16 October 1941
After midnight on 15/16 October, SC 48 made an emergency turn to port, followed before dawn by a turn to starboard, in an attempt to shake off pursuit. This was initially successful, but the pack regained contact in the afternoon of 16 October and again closed in.
Also in the afternoon of 16 October, the first reinforcements arrived, in the form of DesRon 13. This comprised the destroyers , , and , led by (Capt L Thebaud). These were joined later by Thebaud's fifth destroyer, , accompanied by HMCS Pictou. As senior officer present, Thebaud assumed command of the escorts. Though he had seniority, Thebaud had little experience in escort work, and a number of mistakes were made allowing the U-boats to mount a successful attack that night.