The attack on convoy SC 26

During the night of 2–3 April 1941, several hundred miles south-west of Iceland, a group of German submarines attacked convoy SC 26, bound from Canada to Britain. The convoy was slow, numbered 22 or 23 ships (sources differ) and had only a single escort: the armed merchant cruiser HMS Worcestershire, intended to protect it against surface raiders, not U-boats. In under two days, by the evening of 4 April, the submarines sank ten ships totalling almost 52,000 GRT and damaged others. Worcestershire herself was torpedoed and barely limped into Liverpool. On the morning of 5 April the British escort, which reached the scene only after the convoy had been broken up, sank one of the attackers, U-76.

Under 4 April war chronologies record that one of the Atlantic convoys lost “almost 50 per cent” of its ships, and under 1 April they make the general remark that convoy losses remained heavy that month. Both remarks concern the same events. The convoy in question is SC 26: ten ships sunk out of the 22–23 that left Canada amounts to 43–45 per cent, so “almost half” is an accurate description. The attack, however, was not confined to a single day. It began around midnight on 2–3 April, the heaviest losses came on the nights of 2–3 and 3–4 April, and the convoy’s last ship went down on the evening of 4 April. April was indeed a hard month for Atlantic shipping, though, as the figures for the month show, no worse than February and March.

The SC convoys and the gap in the escort

Convoys designated SC (after the port of Sydney on Cape Breton Island, though commonly understood as Slow Convoy) had been sailing since August 1940. They gathered ships too slow to sail in the faster HX convoys from Halifax (PL): old steamers making seven or eight knots, often overloaded and smoking, which in good conditions crossed the Atlantic in two weeks and in a storm much longer. In winter, when Sydney harbour froze, the SC convoys sailed from Halifax. Slow convoys were easy targets: a submarine could overtake them on the surface without difficulty, and stragglers scattered by storms fell prey to single U-boats. In October 1940 convoy SC 7 lost 20 of its 35 ships, the heaviest defeat of the first year of the Battle of the Atlantic.

The weakest point of the whole system, however, was distance. At the beginning of 1941 British escort vessels – destroyers, sloops and the new Flower-class corvettes – lacked the range to take a convoy across the whole ocean. Canadian warships escorted ships only in coastal waters, and escorts from the British Isles went out to meet inbound convoys roughly as far as the 20th–22nd meridian west. In the mid-Atlantic a convoy was usually covered only by a single armed merchant cruiser – a converted passenger liner armed with a few old guns – or by an old battleship or cruiser, meant to protect the ships against German raiders and battleships. Against submarines such cover was helpless: it had neither asdic nor depth charges.

After the setbacks around convoy HX 112 in March 1941, when Joachim Schepke was killed and Otto Kretschmer captured, Admiral Karl Dönitz drew his conclusions. He judged that attacks in the approaches to the British Isles, where strong escort groups and the aircraft of RAF Coastal Command operated, had become too costly, and moved his patrol lines further west, into the mid-Atlantic, to the limit of his boats’ range. There, inbound convoys could be intercepted before they met their escort from the British Isles. SC 26 was the first convoy to sail into this trap.

A wolf pack south of Iceland

Convoy SC 26 left Halifax on 20 March 1941; some of its ships joined from Sydney. It was led by the convoy commodore, George Swabey, in the Magician, and its only ocean escort was Worcestershire, commanded by John Cresswell. The ships were bound for Liverpool, Glasgow, Hull, Leith and London with cargoes on which the life of the British Isles depended: wheat and maize, steel and scrap iron, while two tankers carried diesel oil and fuel for the fleet. Most were British, but there were also Greek, Belgian and Norwegian ships.

Across the convoy’s path, far to the west of the reach of British escorts, Dönitz deployed a patrol line of seven boats: U-46, U-69, U-73, U-74, U-97, U-98 and U-101. Two more, U-94 and the new U-76, on her first patrol, were heading for the hunting ground to join it. Among the commanders was Engelbert Endrass of U-46, who as Günther Prien’s watch officer had taken part in the sinking of the battleship Royal Oak at Scapa Flow. On 1 April U-76, on her way west, sighted the outbound convoy OB 305, but U-boat headquarters did not want to attack so close to the British Isles, within range of British aircraft, and ordered her merely to shadow the ships. Contact was soon lost.

During the day on 2 April U-74, commanded by Eitel-Friedrich Kentrat, sighted convoy SC 26 heading east, sent a sighting report and began to shadow it. Dönitz directed boats from the patrol line onto the convoy. By the evening four U-boats – U-46, U-69, U-73 and U-74 – had gathered around the ships, and at nightfall they began their attack by the same method as in the autumn of 1940: on the surface, at night, at close range – possible precisely because the convoy had not a single vessel capable of detecting and fighting them.

The night of 2–3 April

Endrass struck first, around midnight on 2–3 April. His torpedoes hit the tanker British Reliance, carrying almost 10,000 tons of diesel oil, which sank, though her entire crew survived, and just over an hour later the steamer Alderpool, carrying wheat. The abandoned Alderpool was later finished off by U-73 under Helmut Rosenbaum. The steamer Thirlby stopped to pick up survivors and, although targeted herself, survived the night.

Towards morning the other boats went into the attack. U-74 sank the Greek steamer Leonidas Z. Cambanis, carrying wheat. Rosenbaum hit the British Westpool, laden with scrap, which sank in under a minute – 35 of the 43 men aboard died – and a few minutes later the Belgian steamer Indier, carrying steel, which went down bow first within a minute. Of her crew of 46, four survived. Within a few hours the convoy had lost five ships, almost a quarter of its strength.

Swabey decided that in these circumstances keeping close formation only made the attackers’ task easier, and before dawn he ordered the ships to scatter and proceed independently. As the ships dispersed, U-73 torpedoed the tanker British Viscount, carrying fuel for the Royal Navy to Scapa Flow. She burst into flames that lit up the whole area; her master and 27 of her crew were killed. Moments later U-74 put a second torpedo into Worcestershire below the bridge. The armed merchant cruiser stopped for two hours but stayed afloat and made off under her own power towards the British Isles, where she was met on the way by the destroyer HMS Hurricane. Also on the morning of 3 April, according to the uboat.net records (some studies move this attack to the night of 4–5 April), U-69 under Jost Metzler torpedoed Thirlby, by then sailing alone; two seamen were killed, but the damaged ship reached port.

The hunt for the scattered ships

Dawn on 3 April found ships and submarines strewn across a wide expanse of ocean. The ships were steaming east, the U-boats were trying to find them again, and escort vessels were hurrying west from the British Isles. In the morning Swabey in the Magician gathered eight ships around him and formed them into a convoy again, which during the day met the destroyers HMS Wolverine and HMS Veteran. Command of the escort was taken by Lieutenant Commander J.M. Rowland of Wolverine – the same officer whose group had escorted convoy OB 293 a month earlier, when Prien was lost. Two other destroyers, HMS Havelock and HMS Hesperus, searched the scene of the night battle and picked up survivors from several ships out of the water and from lifeboats. On the same day U-76, still heading west, sank the Finnish steamer Daphne, which was sailing alone – according to some sources a ship that had become separated from SC 26.

Despite the arrival of the escort, the attack continued the following night. The scattered ships were found by boats that had only just joined the chase. Shortly after midnight on 3–4 April U-98 under Robert Gysae sank the Norwegian steamer Helle, carrying pulpwood and steel, whose crew were later rescued by Havelock, and a few hours later the British Welcombe, carrying grain; her master and 19 of her crew were killed. That same night U-94 under Herbert Kuppisch found the main body of the convoy and sank the steamer Harbledown, carrying wheat (17 people were killed), but further attacks were beaten off by the escort. During 4 April further destroyers – HMS Verity, Vivien and Chelsea – and the corvette Convolvulus joined the convoy, and Swabey’s group lost no more ships.

On the evening of 4 April the last victim of SC 26 was the Athenic, sailing alone ahead of the main body. Hit by two torpedoes from U-76, she capsized and sank, but her crew and ten survivors from another ship whom the Athenic had picked up the day before managed to get into the lifeboats. U-76 left without questioning the survivors, because she had heard their calls for help and expected British warships to arrive shortly. Her haste was not enough.

The sinking of U-76

At dawn on 5 April U-76 was charging her batteries on the surface, preparing for another attack on the convoy, when she was spotted by Wolverine. The boat dived at the last moment, but Wolverine attacked with depth charges, followed immediately by a full pattern from the sloop HMS Scarborough. The badly damaged U-boat surfaced and her crew began to abandon her. The corvette HMS Arbutus came alongside in an attempt to seize the boat and capture her cipher documents and Enigma machine – the thing the Royal Navy needed most. But the interior was already filling with chlorine from the flooded batteries, and the U-boat soon sank. Of U-76’s crew of 43, 42 were taken prisoner, including her commander, Friedrich von Hippel; one seaman was killed. Arbutus then picked up the Athenic’s survivors from their lifeboats.

The main body of the convoy – Swabey’s eight ships – reached Liverpool on 8 April, the same day as the damaged Worcestershire. The other surviving ships made their way singly into British and Irish ports over the following days.

The toll

According to the uboat.net records, based on documents from both sides, convoy SC 26 lost ten ships totalling 51,969 GRT, while Worcestershire and the steamer Thirlby were damaged (according to some sources the steamer Eelbeck as well). Of the ships sunk, seven were British and one each Greek, Belgian and Norwegian. Most were carrying grain and steel, and two tankers carried fuel. The human cost is given variously: some studies speak of almost a hundred dead, whereas the sum of the losses from the individual ships recorded by uboat.net comes to almost 150 seamen, including 42 from the Indier, 35 from the Westpool and 28 from the British Viscount. The Germans lost one boat, U-76, almost all of whose crew were taken prisoner.

For Dönitz it was a clear success after a painful March. It showed that a wolf pack could still destroy a convoy if it attacked beyond the reach of the escorts, and it confirmed that he had been right to move his patrol lines west. For the British it was proof that an escort that ended halfway across was not enough.

April in the Atlantic

SC 26 was the heaviest convoy loss of April 1941, but not the only one. According to the uboat.net records, German submarines sank 44 ships totalling almost 248,000 GRT that month and damaged four more. That is about the same number of ships as they sank in February, when they shattered convoys OB 288 and OB 290, and in March. About a quarter of these losses fell on SC 26. Most of the other ships were lost singly – sailing independently or separated from their convoys – and increasingly far from the British Isles: large Type IX boats such as U-105, U-107 and U-124 were operating off West Africa, around Freetown and the Cape Verde Islands, where convoys had weak escorts or none at all.

The Royal Navy itself, whose armed merchant cruisers provided ocean escort, also suffered heavy losses. On 4 April, the same day the U-boats were finishing off ships from SC 26, the German raider Thor sank the armed merchant cruiser HMS Voltaire in a brief action off the Cape Verde Islands. On 13 April U-108 sank the armed merchant cruiser HMS Rajputana in the Denmark Strait west of Iceland; she had been escorting convoy HX 117 a few days earlier, and 42 men were killed. Towards the end of the month, on 28 April, a wolf pack attacked convoy HX 121 south of Iceland, sinking three ships and damaging a fourth, but this time a strong escort hit back at once: that same day the destroyer HMS Douglas sank U-65 with depth charges, with all 50 of her crew. On top of this came losses to mines, aircraft and raiders, and in the Mediterranean to German air raids during the fighting in Greece.

The British responded to Dönitz’s new tactics by strengthening the escort where it was weakest. The key was Iceland, occupied by the British in May 1940. From the spring of 1941 escort vessels were based and refuelled in its ports, at Reykjavík and in Hvalfjörður, and Coastal Command aircraft flew from its airfields. This allowed escorts to go out to meet convoys ever further west. In April the Admiralty also took operational control of Coastal Command aircraft, which made it easier for ships and aircraft to work together over the convoys. The United States, too, was becoming ever more involved: in April it concluded an agreement on the defence of Greenland and extended the security zone patrolled by American warships far to the east, deep into the North Atlantic.

Place in the war

The attack on SC 26 showed clearly where the greatest weakness of the British convoy system lay in the spring of 1941: not in the strength of the escort but in its range. In March, around the well-escorted convoy HX 112, Dönitz had lost his best commanders; in April, by shifting his attacks to the mid-Atlantic, he regained the upper hand and destroyed a convoy whose only protection was a converted passenger liner. The only possible British answer was to close the gap – to provide convoys with an escort across the whole ocean.

This happened over the following weeks. On 20 May 1941 the Admiralty asked Canada to move its escort vessels to St John’s in Newfoundland. Thus was born the Newfoundland Escort Force, command of which was taken in June by the Canadian Commodore Leonard Murray. From then on convoys bound for Britain were escorted in turn by a Canadian escort from Halifax, by ships from Newfoundland to a meeting point south of Iceland, and by British groups from Iceland to the British Isles. On 9 May escort vessels captured from U-110 what they had failed to capture from U-76 – an Enigma machine and cipher documents – which helped the codebreakers at Bletchley Park to read the U-boat arm’s signals and route convoys round its patrol lines. From July shipping losses in the Atlantic fell markedly.

The gap in air cover, however, remained open much longer. Over the mid-Atlantic, beyond the range of aircraft from the British Isles, Iceland and Canada, U-boats could operate in safety until the spring of 1943, when the gap was closed by very long-range aircraft and escort carriers. The SC convoys, slow and hard to defend, fell victim to wolf packs many more times – in the autumn of 1941 SC 42 lost more than a dozen ships. The attack on SC 26 was the first in a series of mid-Atlantic battles that set the rhythm of the Battle of the Atlantic for the next two years.