TU 4.1.15 (LtCdr S.W. Davis, RCN (rtd)) from the Newfoundland Escort Force (NEF) When leaving Sydney on 5 October: Canadian corvettes HMCS Baddeck (K 147) (T/Lt A.H. Easton, RCNR) and HMCS Shediac (K 110) (T/Lt J.E. Clayton, RCNR) Joining from St. Johns with Wabana section on 8 October: British corvette HMS Gladiolus (K 34) (LtCdr H.M.C. Sanders, DSO, DSC, RD, RNR)

Joining from St. Johns on 9 October: Canadian corvettes HMCS Camrose (K 154) (T/Lt L.R. Pavillard, RCNR), HMCS Rosthern (K 169) (Lt W. Russell, RCNR) and HMCS Wetaskiwin (K 175) (LtCdr G.S. Windeyer, RCN) and Free French corvette FFL Mimosa (K 11) (Cdr R.R. Birot, FNFL) Joining from St. Johns on 15 October: Canadian destroyer HMCS Columbia (I 49) (LtCdr S.W. Davis, RCN (rtd))

Reinforcements sent after first U-boat attacks:
Joining from convoy ON-24 on 16 October: TU 4.1.4 (Cmdr L.H. Thebaud, USN) with the American destroyers USS Decatur (DD 341) (LtCdr J.C. Sowell, USN), USS Greer (DD 145) (LtCdr L.H. Frost, USN), USS Kearny (DD 432) (Cdr A.L. Danis, USN), USS Livermore (DD 429) (LtCdr V. Huber, USN) and USS Plunkett (DD 431) (LtCdr W.A. Graham, USN) Joining from convoy TC-14 on 16 October: British destroyers HMS Broadwater (H 81) (Cdr W.M.L. Astwood, RN (rtd)) and HMS Highlander (H 44) (Cdr S. Boucher, RN) Joining from convoy ON-25 on 17 October: British corvettes HMS Abelia (K 184) (T/Lt F. Ardern, RNR) and HMS Veronica (K 37) (LtCdr D.F. White, RNR (rtd)) and Canadian corvette HMCS Pictou (K 146) (T/Lt A.G.S. Griffin, RCNVR)

Escort Group 3 (Cdr A.J. Baker-Cresswell, DSO, RN) relieved escort at Mid Ocean Meeting Point (MOMP) on 17 October: British destroyers HMS Amazon (D 39) (LtCdr N.E.G. Roper, RN), HMS Bulldog (H 91) (Capt A.J. Baker-Cresswell, DSO, RN), HMS Georgetown (I 40) (Lt A.J.R. White, RN) and HMS Richmond (G 88) (LtCdr W.A. Moens, RN (rtd)), British corvette HMS Heartsease (K 15) (LtCdr J.A. Baragwanath, RD, RNR) and British A/S trawlers HMS Angle (FY 201) (T/Lt E. Playne, RNVR), HMS Cape Warwick (FY 167) (T/Lt W.E. Goggin, RNR) and HMS St. Apollo (T/Lt R.H. Marchington, RNVR)

U-73 (Rosenbaum), U-77 (Schonder) *, U-101 (Mengersen) *, U-432 (Schultze) *, U-502 (von Rosenstiel), U-553 (Thurmann) *, U-558 (Krech) *, U-568 (Preuss) * and U-751 (Bigalk)

* U-boats that fired torpedo or used the deck gun

On 5 Oct, 1941, convoy SC-48 left Sydney and went through the Belle Isle Strait into the North Atlantic. On 9 October they ran into deteriorating weather. The next day as a result of ULTRA information the convoy was routed southward around an unnamed patrol line that consisted of U-573, U-374, U-208, U-109 and U-502 and was positioned in this order from Cape Farewell to the southeast. The bad weather during the next days and this unplanned change of course caused ten merchants and three corvettes to lose contact with the convoy and also kept HMCS Columbia from joining as planned on 10 October. HMCS Shediac was unable to regain contact and on 13 October decided to head for Iceland. HMCS Rosthern went off to search for HMCS Shediac but became lost herself. She later found two stragglers and escorted them. HMCS Camrose did the same when she found two stragglers behind the convoy. One of them was the ship of the convoy commodore (Cmdr J. Elliott, RNR) which had been forced to leave the convoy due to steering gear trouble during the night of 12/13 October.

In the meantime the patrol line had been lengthened by the addition of U-568 and U-553 and it was the southernmost boat U-553 that made the first contact with the convoy at 07.05 hours on 15 October. At this time only four corvettes were still with SC-48 and when Thurmann noticed this he immediately attacked without sending a contact report first. Skillfully U-553 entered the convoy from ahead on the surface between the 7th and 8th columns and fired all five torpedoes at four different ships, but the torpedo data computer was not set correctly after firing the second torpedo, so most torpedoes missed. Nevertheless, two ships were sunk and an unconfirmed hit on another was claimed. The U-boat was observed by at least three ships in the convoy and the British motor merchant Silverelm in station #83 unsuccessfully tried to ram when U-553 passed before her bow to attack the W.C. Teagle in station #103. The crew of the tanker observed how the U-boat passed behind their stern and then outran both corvettes on the starboard side of the convoy to get ahead without being sighted or attacked by them. Thurmann then reported the convoy and kept contact until HMCS Columbia finally arrived at the convoy at 16.00 hours, forced her to dive and attacked her with depth charges. At 18.15 hours, U-553 fired her stern torpedo at the destroyer which evaded, slightly damaged the U-boat in a counter attack and kept her down until dusk.

The BdU ordered the four U-boats able to reach the convoy within 24 hours to operate on it immediately, with U-502 and U-568 approaching from north and U-432 and U-558 from south. Four U-boats coming from France (U-73, U-77, U-101 and U-751) were first ordered to head northwards and didn't began operating against the convoy until after U-568 was led to the convoy by bearing signals from Thurmann during the afternoon. Bad weather delayed the approach of the U-boats which could make no more than 13 knots against heavy seas and U-558 was distracted when the fast and unescorted Vancouver Island was spotted at 21.54 hours, chased for one hour and sunk southeast of the convoy.

When the CinCWA realized that convoy SC-48 only had a weak escort, the EG 3 was ordered to relieve the Canadian escort earlier than planned and some escorts were detached from nearby convoys and sent to the convoy in danger as reinforcements including two destroyers from the troop convoy TC-14 and three corvettes from convoy ON-25. But these ships were too far away for immediate assistance, so it was decided to disperse convoy ON-24 which had already passed the patrol line, sending two corvettes to help Vancouver Island and the Task Unit 4.1.4, consisting of five US destroyers, to reinforce SC-48.

During the night of 15/16 October, the contact keeper U-568 also took his chance for an attack and fired a spread of three torpedoes from a long distance at the starboard wing of the convoy, sinking one steamer, before being driven away by star shells from HMS Gladiolus and FFL Mimosa. U-502 and U-553 observed the illumination but were not able to attack themselves because the visibility was soon reduced by rain. At noon on 16 October, three U-boats were in contact when the TU 4.1.4 with four US destroyers arrived as reinforcements and the command passed from the Canadians to the senior officer on USS Plunkett. On their way, some of the US destroyers had passed over U-558 without noticing her. During the afternoon the escorts carried out several sweeps, but all U-boats evaded them by running into rain squalls or by crash diving. Shortly after U-432 and U-558 made contact with the convoy at least two Sunderland or Catalina flying boats arrived in the evening. They were apparently operating at maximum range with only a few bombs because U-558 was the only U-boat that was actually attacked. Four of the five U-boats lost contact when they dived for aircraft, only U-553 stayed up and managed to stay in contact with the convoy during the dark, rainy night. At this time the escort consisted of one Canadian and four American destroyers and one British, one Free French and two Canadian corvettes.

At 23.30 hours, U-553 passed a destroyer ahead of the convoy, possibly USS Plunkett, at only 150 meters distance and then suddenly found herself between the escorts on the port side and the port wing of the convoy. Thurmann then fired three carefully aimed single torpedoes at three tankers, but nothing happened – he thought that the torpedoes ran too deep and passed underneath the vessels, so he set the fourth torpedo to 2 meters and reported a hit on a tanker after observing a column of fire. However, he had underestimated the speed of the convoy and the fourth torpedo apparently missed the intended target too but very likely hit HMS Gladiolus on station astern of the port side of the convoy. While U-553 evaded USS Kearnyby crash diving and passing underneath the convoy, the illumination following this action helped the other U-boats to set up their own attacks and the two destroyers coming from convoy TC-14 to find the convoy. The commander of HMS Highlander then became SoE which led to some confusion among the escorts as they were not all aware that this change of command had occurred shortly after the night attacks began.

At 01.15 hours on 17 October, U-558 attacked the 10th column which then formed the outermost column on the starboard side because the remaining ships of the 11th column had earlier moved to empty stations in other columns of the convoy after some straggled. The first torpedo missed but was claimed to have hit another ship beyond and the second sank W.C. Teagle in station #103. Rym in station #85 changed course to pick up survivors, but had to evade Erviken from station #104 which had already stopped to pick up survivors. U-558 then sank Erviken with the stern torpedo and Rym went to full speed to reach the convoy again, but she was chased by U-432 and U-558 until the latter torpedoed her at 02.14 hours. U-432 having to search for another target, overtook the ships on the starboard side and entered the convoy on the surface from ahead between the 6th and 7th columns. Schultze then fired three bow torpedoes at two ships in the 9th and 8th columns and the stern torpedo at two overlapping ships in the 6th column. Bold Venture in station #92 and Evros in station #64 were sunk in this attack and a hit on a third ship was claimed from a torpedo that had missed the intended target. The U-boat then headed for one of the biggest ships in the convoy and damaged the Barfonn in station #53 with the last loaded bow torpedo.

In the meantime, U-568 tried to get ahead on the port side of the convoy but was disturbed each time by a destroyer with two funnels which was identified as a British destroyer of the A or D class. At 04.15 hours, Preuss fired a spread of four torpedoes from more than 2000 meters, observed one hit and claimed to have seen the destroyer break in two and sink. In fact, USS Kearny just completed a maneuver to avoid a collision with a corvette when she was hit by a torpedo and temporarily disabled, but did not sink. U-432 had stayed close to Barfonn when she remained afloat, reloaded a torpedo tube on the surface and then fired a coup de grace at 04.48 hours. The hit ignited the fuel oil carried by the tanker, which exploded and illuminated the whole area astern of the convoy. U-558 found herself exposed while trying to get into an attack position on two stopped destroyers but managed to escape at full speed without being noticed. U-432 was sighted by HMS Broadwater, forced to dive and damaged by her depth charges at 05.30 hours. Around the same time, U-553 attacked a destroyer ahead of the convoy, possibly HMS Highlander, with her last two torpedoes, but missed and was chased away into a rain squall. USS Livermore and USS Decatur carried out several depth charges attacks during the night on sound contacts. It is possible that the submerged U-432 was attacked in some of them or they were carried out against non-sub targets – however, no U-boat was damaged by them.

During the night more reinforcements arrived at the convoy. One was USS Greer which was ordered to assist USS Kearny and the three corvettes from ON-25 which came up from astern. Two of them immediately began to rescue survivors from the torpedoed ships together with HMCS Baddeck, while the third corvette HMCS Pictou sighted and chased U-568, was missed by her stern torpedo at 06.02 hours and then attacked the U-boat unsuccessfully with depth charges after it crash dived. HMS Highlander and HMCS Wetaskiwin joined the hunt but were unable to obtain a contact. HMS Abelia, however, made contact with the submerged U-432 and carried out three depth charge attacks – without causing further damage to the U-boat. HMS Veronica located the drifting Rym which had remained afloat on her load of timber and stood by her until dawn to take off the last survivors. At 07.27 hours, U-558 carried out the last attack of the night when they fired a torpedo at a small straggler, but it became a surface runner so the U-boat fired its last two torpedoes with a deeper setting that apparently passed underneath the target. All four U-boats in contact with the convoy that night carried out attacks and claimed seven merchants and a destroyer sunk and possible hits on two more ships – confirmed are the loss of six merchants and a corvette and one destroyer damaged.

At dawn the SoE tried to reform the escorts around convoy SC-48, which now consisted of 31 ships, but they were in complete disarray. USS Greer had left to escort the damaged USS Kearny to Iceland and most of the corvettes were lagging behind the convoy after carrying out rescue work, only HMCS Camrose, FFL Mimosa and HMS Abelia managed to rejoin before the four destroyers of EG3 arrived to relieve the escorts. During the morning, U-502, U-101 and U-751 made contact with the convoy which was then in range of aircraft based in Northern Ireland. At dawn Sunderland flying boats had appeared over the convoy and were later joined by three Catalinas of the US Navy based in Iceland, which carried out no attacks but their presence forced every U-boat chasing the convoy to dive now and then. Sometimes the U-boats sighted up to four aircraft at a time. Only U-558 was able to keep contact for a while but she was out of torpedoes. U-553 was in the same situation and she soon gave up and began her return voyage, passing through the area of the attacks in the afternoon sighting large oil patches, much debris and many floating bodies. The same area was searched by the three remaining US destroyers after they were detached from the convoy around noon, sighting a wreck which was identified as capsized U-boat and sunk by gunfire, but this was more likely the still floating bow of Barfonn.

In the afternoon, HMCS Columbia, HMCS Baddeck and HMCS Pictou left because they were low on fuel while the remaining corvettes were asked to remain with the convoy for one more night, but HMS Abelia and HMS Veronica were too far behind and only reached the convoy the next morning. The latter encountered U-751 at 17.00 hours, forced her to dive and unsuccessfully attacked with depth charges. This attack was heard by the nearby U-502 which had earlier dived for aircraft. Around the same time, U-432 tried to chase a fast independent merchant but due to her damaged state could only make 12 knots and soon lost sight of her. Because no U-boat was still in contact with the convoy, the BdU ordered each of them to search in different sectors in the evening. In the meantime the remaining ships of the relieving escort group had joined. The escorts now consisted of four destroyers, one corvette and three A/S trawlers of EG3, three corvettes from the original escort and the two destroyers from convoy TC-14 – led by the commanding officer of HMS Highlander.

U-568 made contact for a short time but lost the convoy again in rain squalls. The remaining U-boats operated on her transmitted sighting report, but the merchants were not sighted due to bad visibility. U-101 alone made contact with the rear escort of the convoy at 01.00 hours on 18 October. For three hours she tried to overtake the convoy and after several approaches were frustrated by the escorts, Mengersen fired a spread of four torpedoes at HMS Broadwater at 04.20 hours. The destroyer was hit by a torpedo losing her complete bow and the three A/S trawlers were sent to her assistance. The detonation had been observed by U-73 and U-77 and the latter arrived at the scene after 90 minutes but it was too dark to see more than two shadows. Nevertheless the U-boat carried out an unsuccessful attack with one torpedo against one of the vessels at 06.33 hours, but made no further attacks after they were recognized as small escorts. This attack was not noticed by the A/S trawlers, which finished their rescue work and then scuttled the wreck of the destroyer. During the morning the corvettes not belonging to EG3 were detached to land survivors and resupply and HMS Abelia left to join convoy HX-154. Some stragglers even managed to rejoin during the day, among them the convoy commodore's ship.

At daylight the first aircraft arrived again over the convoy which was soon also covered by faster Blenheim or Beaufort bombers – each U-boat had to evade aircraft by diving at least once during the day. At 09.05 hours, U-77 spotted a straggler and when chasing this ship sighted the convoy, reporting its position and course. At the same time, U-432 reported being in contact with another part of the convoy after spotting columns of smoke in a more westerly position. Assuming the convoy had split in two parts, most U-boat commanders decided to operate on the report of U-432 because it was closer and the aircraft made it impossible to reach the position of U-77 anyway. This was proven when this U-boat lost contact with the convoy after being forced to dive by a flying boat and was kept submerged until dusk. U-751 and U-558 soon identified the columns of smoke as A/S trawlers and corvettes, but U-432 still reported them as part of the convoy until the three U-boats met each other around 19.00 hours and the commanders discussed their observations, coming to the conclusion that had all chased the same group of small escorts – the A/S trawlers that had remained behind to rescue survivors from HMS Broadwater. After convincing the BdU that the convoy had not split in two parts, the U-boats were ordered to operate on the last report of U-77 during the night and then break off the operation if not in contact at dawn. However, most commanders soon realized that they were too far away and one after another gave up the chase. The last ones were U-502 and U-568 which gave up around 08.00 hours on 19 October.

Eventually the BdU ordered all U-boats to break off the operation and to report their state of fuel and torpedoes. Apart from U-553 and U-558 which were out of torpedoes all the other U-boats were ready for further operations and formed the wolfpack Reissewolf. Five U-boats carried out attacks on convoy SC-48 or its escorts and claimed the sinking of eight freighters (42,000 GRT), three tankers (25,000 GRT) and two destroyers and hits on two more merchants. The BdU also asked for details of their encounters with destroyers because the Americans reported that one of their destroyers had been torpedoed and not being at war with Germany this case had to be investigated as an attack would have been against the standing orders. No one could be blamed because the Americans actively participated in the convoy battle, firing star shells and dropping depth charges on sound contacts and making it impossible for the U-boats to distinguish between the Allied escorts and the allegedly neutral US destroyers.

The night of 18/19 October remained calm but the ill-fated convoy SC-48 had even more to suffer when the wind increased during the day and a gale hit the convoy before it was able to reach the North Channel, forcing its ships to hove to for the night and damaging several of them. The morning of 20 October found the convoy badly scattered. The ships did not reform and continued independently or in small groups to their destinations. Among the ships with weather damage were the convoy commodore's ship and a Greek freighter that lost its rudder and received help from HMS Georgetown. Escorts suffered from the heavy weather themselves. For example some frames, side plates and upper deck fittings on HMS Richmond were damaged and HMS Amazon was disabled when her steering gear broke and she had to be assisted by HMS St. Apollo. Finally all ships reached port by 22 October.

In retrospect convoy SC-48 could easily have lost even more ships because the escorts were unable to protect the ships from the U-boats, which carried out most attacks without being detected or attacked by the escorts and in three cases even carried out successful attacks on them. On one side this was possible because only a few of the escorts were yet fitted with radar and the new Type 271 centimetric radar was only carried on HMS Heartsease but was out of order. This was compounded by several of the other warships also having problems with their ASDIC or radar sets. For example HMCS Camrose had both systems out of order at one point during the battle. Then again the participation of the US Navy in an undeclared war revealed several weak points as the US commanders lacked experience and remained very close (less than a mile) to the convoy during the night, thus allowing the U-boats to come into firing range before being visually detected and due to their proximity to the convoy the star shells they fired illuminated the merchants instead of the U-boats. Furthermore the tactic of dropping single depth charges or a series of depth charges in order to scare away submerged U-boats proved to be ineffective because the U-boats were attacking the convoy on the surface. To add to the confusion, shortly after the first attack on the night of the main attack, more reinforcements arrived and the command was passed to the senior officer on HMS Highlander – a fact that was for a long time not known to every escort, especially because the stronger radio transmitters of the US warships interfered with the British sets and proper coordination between the escorts became impossible. The commander of EG3 also criticized the directive to pass the command to the senior officer because he was not allowed to take over command from HMS Highlander when his group relieved the other escorts and in his opinion the loss of HMS Broadwater was a consequence of this rigid command structure.

When leaving the convoy, Cmdr Thebaud sent this radio message to the British commander: "Torpedoing of USS KEARNY last night may well make history and put us openly and fully in the war. Best of luck." His prediction proved to be wrong, the attack made it into the headlines of the press but politically it had no great influence – however, the undeclared war between the US Navy and the Kriegsmarine escalated further, culminating in the loss of USS Reuben James with heavy loss of life exactly two weeks after the USS Kearny incident.