The Secret Capture

by Stephen Roskill

  The Italian submarine Galileo Galilei being towed into Aden, after her capture by H.M.S. Moonstone and other ships, 19th June, 1940

  The surrender of U.570 to Hudson S. of No. 269 Squadron of Coastal Command, 27th August, 1941

  The capture of the Italian submarine Perla by H.M.S. Hyacinth, off Beirut, 9th July, 1942. The British prize crew is working the submarine from her conning tower while the Italian survivors sit on the fore deck.

  The Italian submarine Bronzo in tow by H.M.S. Seaham, off Augusta, Sicily, 12th July, 1943

  H.M.C.S. Chilliwack boarding U. 744 in the Atlantic, 6th March, 1944

  The corvette’s masts can just be seen beyond the U-boat.

  Convoy OB.318

  on passage south of Iceland, May, 1941

  H.M.S. Bulldog, senior officer’s ship, 3rd Escort Group, leaving Iceland to meet convoy OB.318, 7th May, 1941

  Commander

  A. J. Baker-Cresswell, R.N., Senior Officer 3rd Escort Group, on the bridge of H.M.S. Bulldog

  H.M.S. Bulldog. Taken before the war

  H.M.S. Aubrietia

  U.110 breaks surface. H.M.S. Bulldog lowering her whaler with boarding party. Taken from H.M.S. Aubrietia

  Survivors from U.110 in the water.

  Taken from H.M.S. Aubrietia

  H.M.S. Bulldog taking U.110 in tow

  Sub-Lieutenant D. E. Balme, R.N., leader of H.M.S. Bulldog’s boarding party

  Kapitänleutnant Fritz-Julius Lemp of U.110. The Iron Cross he is wearing was found on board U.110 and was returned to his sister by Captain Baker-Cresswell in 1958

  It is difficult to be precise regarding the exact screening diagram ordered by Bockett-Pugh; for, as with virtually all escort groups at that time, it was peculiar to his own command and no copy of his orders has survived. It is likely, however, that while he himself in the Westcott preserved complete freedom of manoeuvre around the convoy, his other two destroyers (the Campbeltown and Newmarket) were stationed a mile ahead of it, the sloop Rochester was the same distance astern, and the five corvettes and the trawler Angle were on the bows and beam of the convoy, three on each side. We know, at any rate, that the 7th Escort Group was in such a formation when it turned the convoy over to the 3rd Escort Group on the evening of the 7th May.2

  Throughout the daylight hours of the 5th, Coastal Command aircraft continued their vigil above and around the convoy as it steamed steadily west in good formation. In fact the records of No. 15 Group show that the convoy was far better looked after than either the merchantmen or the surface escort realised at the time; for a Whitley of No. 612 Squadron, five Hudsons of Nos. 220 and 269 Squadrons and a continuous escort of Blenheim fighters from Wick all accompanied it throughout the day. It is, indeed, a common experience for surface vessels not to realise how closely they are guarded by friendly aircraft, much of whose activity may take place at the limit of visibility, or even beyond the horizon. A good example of this phenomenon occurred that afternoon when, at 2.35 p.m. Hudson O of No. 269 Squadron, commanded by Sergeant C. H. Eatley, sighted a U-boat on the surface some fifty miles astern of the convoy while flying outwards to join the air escort. This was almost certainly U.141, which was proceeding back to Norway round the north of Scotland after a patrol in the Atlantic. Sergeant Eatley at once dropped three depth charges and reported the sighting, whereupon the Commander-in-Chief, Home Fleet, ordered two of his destroyers, the Electra and Escapade, which were on the way to meet convoy HX.122, to make for the position at high speed to co-operate with the aircraft, and No. 15 Group sent out a Whitley to join the searchers. But the U-boat had not been sighted again by the time that the destroyers had to break off the hunt to meet their convoy.

  The Admiralty’s assessment of Sergeant Eatley’s attack was that the U-boat was “ probably seriously damaged,” which we now know to have been very near the mark; for U.141’s report states that “ two bombs (sic) fell 20 metres to starboard,” and caused such damage to a fuel tank and to the diesel engine cooling system that her Captain reported to U-boat headquarters that he could not reach Bergen. Dönitz therefore ordered him to make for Lorient, where he arrived safely on nth May. The Westcott had also picked up Sergeant Eatley’s sighting report, but the enemy was already well astern of the convoy and Commander Bockett-Pugh did not therefore consider it necessary to take evasive action. It is plain, however, that some earlier sign of U-boat activity in the way of the convoy had reached Derby House; for at 9.38 a.m. that morning Admiral Noble diverted it to the south of the track originally ordered by the Admiralty “ to avoid possible U-boat threat.”1 It is possible that this prescient action kept OB.318 clear of trouble from U.147, which was not very far away at the time.

  That same afternoon the Western Approaches Command arranged for the change-over of escorts in mid-Atlantic, by ordering the Naval Officer in Charge, Iceland, to sail the 3rd Escort Group so as to meet the convoy in 61° 07′ North 23° 37′ West (about 200 miles south of Reykjavik) at 6 p.m. on the 7th. Admiral Noble signalled what the convoy’s course should be at that time, and gave the direction from which the new escort was to approach the rendezvous, thus minimising the risk of the convoy and the relief escort missing each other.

  With the ten ships of the 7th Escort Group now disposed around our convoy, their Asdic sets constantly probing the depths, while the watchkeepers in Derby House moved the symbol indicating the convoy’s progress every four hours, and the Admiralty’s centralised intelligence organisation listened alertly for the slightest sign of the enemy they knew to be lurking on the convoy’s route, it is time that we looked on “ the other side of hill ” to see what was happening in Dönitz’s headquarters at Lorient, and how the U-boats then in the North Atlantic were disposed.

  1 See Map 1 (front end paper).

  1 On the dates with which we are principally concerned in this narrative (May 1941) local time in the British Isles was Double Summer Time (G.M.T. plus 2 hours). The German Navy was keeping German Summer Time, which was also 2 hours ahead of G.M.T. Because local times varied as our convoy operation moved west it has been thought best to standardise all the times given in the narrative on the basis of G.M.T. Though this gives by far the most convenient standard it does have the disadvantage that it ignores changes in time due to changes in longitude.

  2 The Angle actually belonged to the 3rd Escort Group, and was originally intended to rejoin her group in Iceland. During the convoy’s passage she was, however, ordered to remain with it and she actually met her consorts at sea on 7th May.

  1 The first D.S.O. was awarded to Bockett-Pugh when he, still in the Westcott, sank U.581 off the Azores on 2nd February, 1942; the second was for sinking a French submarine off Oran during the North African landings on 8th November, 1942, and the third was for his services in the Normandy landings of June 1944.

  1 See Diagram 3 (back end paper) for the composition and formation of Convoy OB.318 on sailing.

  1 On 5th May off the Butt of Lewis sunrise was at 6.23 a.m., and sunset at 10.20 p.m. British Double Summer Time.

  2 See p. 86 and Map No. 1 (front end paper).

  1 See Map No. 1 (front end paper).

  CHAPTER V

  The Enemies in the Way

  ON 5TH May, 1941, when OB.318 emerged from the Minches into the North Atlantic, there were probably nine U-boats on patrol in the Atlantic north of latitude 55 degrees.1 Three of these were cruising in about 25° West, but all the others were in the north-western approaches to the British Isles, which we may define as covering a 90-degree arc of 600 miles radius with its centre in the Clyde. There were five more in the south-western approaches, and several others were still further south, approaching or leaving the Bay of Biscay bases. Two of the northern boats (U.75 and U.123) were actually withdrawing towards the French coast, but two others (U.556 and U.111) had recently left Germany for the Atlantic by the northern route round the Shetlands and Faeroes, and reached their patrol areas within the next two or three days. The total strength available to work against ou
r convoy between 5th and 9th May thus remained fairly constant; but as only four boats (U.94, U.110, U.201 and U.556) were actually involved in attacks on it we need not concern ourselves greatly with the movements of the other five.

  On the day that our convoy took up its ocean formation off Cape Wrath Dönitz’s staff reviewed future prospects in the Atlantic Battle. They noted in their War Diary that our convoys “ generally dispersed in longitudes up to 25° West,” and they therefore deduced that “ whereas the greatest concentration (of British shipping) would be found off the Newfoundland Banks or in the approaches to the North Channel to the Irish Sea, the greatest spread occurred between 25° and 30° West.” As our homeward convoys were generally being met by an anti-submarine escort in about 30° West, and our outward convoys were dispersing in the same longitude, the U-boat Command’s deductions were, broadly speaking, correct. What the enemy particularly wanted to do was to catch our homeward shipping before it was joined by a close escort, and our outward convoys after their escorts had withdrawn; for the merchantmen would then be at their most vulnerable. U-boat Headquarters were perturbed about the increasing strength and effectiveness of our escorts. “ Defence by (British) sea and air forces has been observed to an increasing degree,” they noted on 6th May. “ These defensive measures,” they continued, “ have resulted in boats being driven off in various cases, even though they managed to approach a convoy … There have been no great successes lately.” On the same day Dönitz’s staff repeated their frequent complaints about the failure of the Luftwaffe to co-operate effectively. Such air reports as were received were, so they said, generally valueless, because of the inaccuracy of the positions given. Thus “ the Luftwaffe gives no help in guiding the U-boats to the enemy.”

  For operational purposes the U-boat Command divided the Atlantic into a number of zones, each designated by a two-letter symbol; and the zones were all sub-divided into a number of rectangles, each of which was identified by two figures. The rectangles could be further sub-divided into smaller spaces, to enable a spot in the ocean to be exactly pin-pointed, but these were not marked on the special charts issued to all U-boats. The principle on which the German charts were constructed is shown in the diagram below.

  By a simple signal such as “ Convoy in AK.2799 ” Dönitz’s headquarters could indicate to the patrolling U-boats the presence and position of any convoy or naval force; and we could only identify the threatened units by measuring the direction from which the U-boats had signalled to their base. But capture of one of the German gridded charts would, of course, at once give us a more accurate idea of what their intentions were. Surface ships and aircraft could then be sent to search for the enemies with good prospects of success, and threatened convoys could be diverted on to safer courses. It will not need much imagination to appreciate the scope of the benefits thereby gained to our cause.

  It is with Zones AM, AL and AK on the German charts that we are here principally concerned; for they covered the Atlantic Ocean between latitudes 51° and 61° North and longitudes 5° to 40° West. Virtually all our North Atlantic shipping thus had to pass through those zones.

  On 6th May Dönitz ordered six boats (U.93, 94, 97, 98, 201 and 556) to proceed to square AK in the central Atlantic where they were to be joined later by U.109 and 111 from Germany and U.43 and 74 from France; but in fact this dangerous concentration in one area was not fully implemented, because some of the boats were diverted to other duties. In spite of his lack of confidence in the Luftwaffe’s co-operation Dönitz asked at the same time for reconnaissance flights by the long-range FW.200 aircraft stationed at Stavanger in Norway and near Bordeaux, with the object of reporting traffic approaching or leaving the British Isles. Since the fall of France the Italian Navy had been anxious that its submarines should play a part in the Atlantic battle, and a number of them had come to French bases for the purpose. But the Germans had found from experience that, if they tried to co-ordinate operations with the Italian submarines, the latter were liable to be more of a handicap than an advantage; and on the same day Dönitz allocated to them an area well to the south of our main convoy routes. “ Here,” he remarked scathingly, “ they cannot adversely affect our own operations.”

  Early on 6th two German reconnaissance aircraft reported an inward-bound convoy in about 60° North 13° West; but their fixes were about 100 miles apart, and did not therefore greatly help the U-boat command. They must in fact have been reporting either the fast convoy HX.122 or the slow convoy SC.29, or possibly both of them; for they were both approaching the west of Scotland at that time.1 At 1.57 p.m. next day, the 7th, U.95 reported a convoy, almost certainly SC.29, to have been 120 miles west of the Hebrides at 8.40 that morning, on a south-easterly course. Dönitz realised that the convoy had by that time progressed too far to the east to enable an attack to be organised, and he therefore took no action; but in the Admiralty U.95’s signal had very interesting repercussions. We will return to the matter shortly, for we must see how our convoy had meanwhile been progressing since we left it steering north-west from the Butt of Lewis on the evening of the 5th.

  That day Commodore Mackenzie seized the opportunity to exercise the merchantmen in carrying out emergency turns in formation. This was by far the most likely manoeuvre to be called for, and was never an easy one to accomplish without losing cohesion—especially by night. At 4 p.m. course was altered from N. 80° W. (true, to S. 89° W. in accordance with Admiral Noble’s alteration to the route originally given by the Admiralty. The night of the 5th-6th passed quietly, with the escorts carrying out their usual dusk searches; but two evasive alterations of course were made during the dark hours with the object of shaking off any pursuers. At dawn on the 6th the convoy was steering N. 76° W. (true), and there was still a Coastal Command Whitley patrolling watchfully overhead; but she had to return to base soon afterwards, and during the rest of the day Coastal Command could not provide any close air escorts. The reason was that No. 15 Group was very busy protecting the homeward-bound convoys HX.122 and SC.29, either or both of which had, as we have already seen, been reported by the enemy; and on this day the air escorts of SC.29 actually had several engagements with German long-range FW.200 reconnaissance-bombers. But OB.318 was not entirely neglected; for Catalinas and Whitleys flew several sweeps from their Scottish bases out to the north-west, and on one of them our convoy was sighted and reported to be in no trouble of any sort. The only interesting event to take place around the convoy on the 6th was the sighting by the Rochester of a floating torpedo. Bockett-Pugh lowered a boat from the Westcott and picked it up successfully, with the intention of forwarding it to our technical intelligence organisation.

  Throughout the following night the convoy plodded steadily on at 8 knots. By the morning of the 7th it had got beyond the range of No. 15 Group’s Hudsons working from Scotland, but was escorted for part of the forenoon by one of the Sunderlands stationed in Iceland, until the threat of fog at its base caused it to be recalled. This was unfortunate, since had the Sunderland been able to stay with the convoy she might well have sighted, later in the day, a slim, dark shape lying low in the water ahead of the convoy’s track; and she might thus have been able to give warning of the presence of Kapitänleutnant Herbert Kuppisch’s U.94.

  At 8.30 a.m. on the 7th the Iceland section, consisting of the merchantmen Iron Baron and Atlantic Coast and the Dutch ocean tug Zwarte Zee left the convoy, and proceeded in company towards Reykjavik. Shortly afterwards the Westcott sighted an empty lifeboat, bearing the name Terje Viken. Throughout the war the Atlantic was all too full of such flotsam; and often it could have told tragic tales. In the present case the boat undoubtedly came from the United Whalers’ Company 20,638-ton factory ship, which had been sunk about 400 miles to the east on 7th March. During the day the escort vessels also sighted and sank several mines, which had probably broken adrift from the barrage we had been laying between Iceland and the Faeroes. Ever since the summer of 1940 we had been expending a considerable e
ffort on this enormous minefield. Its object was to impede the passage of U-boats into the Atlantic by the northern route; but we now know that it was a singularly unprofitable undertaking, for during the entire war only one enemy was sunk in it.

  During the forenoon of the 7th Bockett-Pugh’s ships several times reported Asdic contacts, and in some cases attacked them. But by the early afternoon the group commander became convinced that they “ were all hunting whales, or possibly patches of cold water,” and he ordered the hunters to rejoin the convoy. Fifty-two depth charges were, however, expended —a depletion of their outfits which some of the ships were to regret later.

  We saw earlier how U.95 made a sighting report on one of our homeward convoys (HX.122 or SC.29) far to the east of OB.318 at 1.57 p.m. on the 7th. The Germans always prefixed such messages with an accented letter E in the morse code (dot dot dash dot dot), and we called them “ E-Bar messages ” from the British custom of writing the accented E with a bar over it thus (ē). As soon as such a message was heard by the Admiralty’s interception service, and the direction-finding stations had taken bearings of the transmission, so enabling us to fix the sender’s position approximately, it was plotted in the Submarine Tracking Room. A glance at the plot would now probably indicate which convoy the enemy had sighted, and action would at once be taken to warn the escort and to divert the convoy. But in the present case things did not work out quite that way. The listening stations picked up U.95’s report correctly, but the direction from which it came was about the same as that of our convoy, and the Admiralty therefore estimated that it was OB.318 which had been reported. Actually it was some 325 miles to the west of U.95’s position at the time. Had the Admiralty been able to decode the message such a mistake would have been impossible; for we now know that U.95 reported the convoy she had sighted to be steering south-east. The result was that, at 3.04 p.m. the Admiralty sent an “ Immediate ” signal to Bockett-Pugh, and also to Baker-Cresswell’s 3rd Escort Group, which had left Iceland early that morning to join the convoy, saying that OB.318, or possibly Baker-Cresswell’s ships, had been reported by a U-boat. At the same time the Admiralty also used its powers of direct operational control to order the convoy to make an evasive turn to starboard until it reached latitude 62° North, and then to steer due west. The message was received by the Westcott and also by Baker-Cresswell’s Bulldog at 3.51 p.m., and the former communicated it to the Commodore. About an hour later Mackenzie wheeled his convoy round from N. 70° W. (true) to N. 42° W. Bockett-Pugh did not consider the turn drastic enough, and wanted the Commodore to alter further to starboard; but Mackenzie adhered to his decision. Baker-Cresswell also expected the convoy to make a bigger alteration, and allowed for it to be steering about N. 27° W. when he started to search for it.