Beginners Luck ? The Destruction of U-714

On March 14, 1945,  some four hours after leaving the Tyne, HMS Natal, a brand new frigate with a green crew carried out an attack on a U-boat some four miles off Burnmouth, Berwickshire. The U-boat was sunk. Natal‘s attack was subsequently described in ‘South Africa’s Fighting Ships’ as, ‘a feat unique in the annals of the Royal Navy’.  Roskill, the Official Historian described how Natal, “Sent her [the U-boat] to the bottom with a promptitude, which would have done credit to a much more experienced crew”. The role of HMS Wivern in this affair is totally ignored. and the factors which made this sinking remarkable also made it controversial. There was a lingering belief within Royal Navy circles that political expediency triumphed over material fact in ascribing the ‘kill’ to Natal alone. Using available evidence it is proposed to examine this charge in detail to discover which ship was responsible for sinking the U-boat.

The Background

By March 1945 only a fool or a fanatic believed that Germany could  win the war. The much-vaunted wonder weapons were never going to be deployed in sufficient numbers to tip the balance back in Germany’s favour.  While the army was being hammered on all fronts, Donitz pressed home his inshore campaign in British coastal waters, utilising U-boats based in Norway. Donitz used his U-boat fleet to play for time, to cause havoc in British coastal waters until the Type XXI and XXIII U-boats entered service. Few Kriegsmarine planners thought these new submarines would turn the War in Germany’s favour but they could prove a useful bargaining chip in any future ceasefire arrangements. And so the inshore campaign saw the return of U-boats to the East coast of Britain. Type II U-boats had operated off the coast until 1940 (See ‘Terror off the Tyne II’) when more Type VIIc boats became available and the attention of Kriegsmarine planners turned first to the West coast of Britain and then to the Atlantic.

The post D-Day threat to the German Atlantic bases witnessed the gradual retreat of the U-boats to Norway. Many of the U-boats which participated in this North Sea endgame were based with 33 Flotille at Horten near Oslo. U-714 under the command of  Kplt. Hans-Joachim Schwebcke arrived there in February 1945, just a month before her last patrol. Details of U-714 are given in the Appendix at the end of this article, it is not proposed to elaborate on them here except for observing that the boat was somewhat elderly. She was not a purpose built Atlantiker like U-1274 but an upgraded VIIc equipped with a Schnorchel and a Wintergarten. Twenty-seven year old Hans-Joachim Schwebcke had carried out several patrols but achieved no sinkings to date. The pressure on him must have been significant at this stage. In October 1944 the boat had carried out a patrol in the difficult coastal waters between Lands End and Trevose Head but had not seen any traffic to attack. The crew of U-714 did know what is was like to operate in seas where the Allies had near total air superiority.

Schwebcke was however an experienced Commander and his crew contained a number of seasoned veterans in the form of IWO Lt. Arno Rickmann and Oblt. Ing. Muller. A second engineer officer, Lt. Heinrich Bentz was present on this patrol, possibly under instruction.

Schwebcke and his boat benefited from some experienced petty officers which is just as well as most of the ratings were under twenty-five (See Crew List in Appendix). The crew of U-714 may be seen as a typical cross-section of a U-boat crew of this period with the conscript element outstripping that of the volunteer.

U- 714 left Horten on 3 March 1945 for operations off the East coast of Scotland and North East England. Schwebcke almost certainly crossed the North Sea on the latitude of Aberdeen, prior to shaping a South Westerly course designed to penetrate the British mine barrier via Gap A. We know this because this was the standard route taken by U-boats engaged in the inshore campaign at this juncture. It is likely that the Schnorchel was used throughout this journey until the boat was off the red cliffs of Arbroath, a useful feature regularly noted by U-boat navigators.

Britain had declared a protective coastal minefield down the East coast as early as September 1939. At the time of this declaration this minefield existed more in the imaginations of naval planners than in fact. However since 1939 this minefield had been gradually formed into a reality with real and effective mine barriers. BdU staff were inclined to be sceptical about British minefields. They had little evidence of British mine-laying activities and reasoned that any mines laid back in 1939-1940 would have automatically de-activated by March 1945. Luftwaffe reconnaissance had indicated the presence of two gaps used routinely by warships and fishing boats. The northerly, known to the British as ‘Gap A’, although heavily patrolled by aircraft and anti-submarine vessels offered a certain route to penetrating any remaining coastal mine barrier. From the inception of the inshore campaign to the end of the War, this became the standard route adopted by Norway based U-boats attacking shipping on the British East coast.

Close to mid-day on March 10, while transiting ‘Gap A’, Schwebcke was in the Swept Channel North of the River Tay roads when he encountered elements of a Southbound convoy, FS 1753 (a). A handful of ships was steaming down the Swept Channel to Methil to rendezvous with the main convoy to Southend due to sail next day. The ships were escorted by Dundee trawlers but there were no destroyers. At 12:02 there was an explosion two miles North of Buoy No 25. One of the convoy escorts rolled over and sank. The ship was the Royal Navy (ex Norwegian) Auxiliary Fleet Minesweeper Nordhav II (FY1906) attached to the Dundee based 71st Minesweeping Group. The ship, a mere 425 tons, would not ordinarily have been considered worthy of a torpedo. It is highly likely that Schwebcke was either aiming at a larger target but the unfortunate Nordhav was struck instead. Alternatively Schwebcke may have fired a Typ IIIa FaT 2(Fluecher absuchender)  torpedo which followed its pre-programmed pattern before homing in on to the unfortunate vessel’s screws. Six men, including Captain A. Olsen died. The other casualties were; Odd Hansen, A. Korneliussen, R. Meyer, Stoker John Purcell and Signalman John Taylor. Schwebcke and his crew had broken their duck.

The Norwegian minesweeper Syrian rescued the seventeen survivors, landing them in Dundee Docks. In fact this was to be a somewhat unlucky convoy. The Canadian Taber Park, 2,878 tons, hauling coal from the Tyne, fell victim to a Seehund torpedo off Southwold. There were only four survivors.

U-714 meanwhile continued her journey down the Swept Channel looking in vain for targets off the Forth. We do not know her precise movements but it is likely she patrolled off May Island in the hope of attacking a Methil convoy. There are no known U-boat sightings or reports during this period but Schwebcke must have taken the decision to patrol between St Abb’s Head and the Farne Islands. What is certain is that on March 14, Schwebcke and his boat were off Burnmouth, just North of Berwick, stalking Methil-Southend convoy FS 1756. This convoy consisted of SS Don, Empire Lagoon, Empire Shepherd, Glaisdale, Grainton, Herman Melville, Magne and Fort Walsh. Both Herman Melville and Fort Walsh were well over 7,000 tons. The convoy was guarded by destroyers provided by the Rosyth Escort Force. The routine procedure on FS/FN convoys was for the ‘V’ and ‘W’ class destroyers to escort the convoy as far as the Humber where other units would take over. By this stage of the War Rosyth escort force tended to be First World War vintage destroyers. While it would be untrue to write that they were unfit for any other duties, it is fair to observe that having seen service in two World Wars, ships of this class had their limitations. For instance ASDIC equipment fitted in 1942 had been upgraded rather than replaced.

One ship attached to the Rosyth Escort Force was the 1919 vintage destroyer, HMS Wivern (Capt. C.C. Anderson) which was to play a major role in this story. Wivern had served in several sea-war theatres and had been in action since the declaration of war. Wivern had been badly damaged on February 22, 1944 off Cape Espartel, while attempting to rescue the crew of HMCS Weyburn, a Canadian warship. A couple of depth-charges had exploded as Wivern moved alongside. A long refit had followed with the ship joining the Rosyth Escort Force in November 1944.

On 14 March, the 1,191-ton Swedish SS Magne (1912 – Stockholms Rederi A/B Svea, Stockholm) was torpedoed and sunk just north of Berwick in position 55° 52’N 01° 59’W. Magne was at the rear of one of the columns. It seems likely that Schwebcke closed the convoy then fired a FaT torpedo. Ten of Magne’s crew of twenty-one were lost; V. Ericsson, Master, F. Urban, Fireman and Trimmer, L. LLewelyn AB, L. Lovberg Fireman and Trimmer, A, Nilsson, Greaser, A. Olsson, Second Engineer J. Pedersen Fireman , A. Schouten, Third Engineer Officer, S. Svenssen AB. Magne had been carrying a cargo of potatoes, hemp and zinc ingots, the latter ensuring that the vessel sank in minutes.

Sheaf Crown, the vessel ahead of Magne immediately transmitted a U-boat alarm at 13:25. The sector was beyond the range of Schnellboot Flotillas. While mining could not be ruled out, no U-boat had attacked in these waters since 1940. HMS Wivern detached from the rest of the convoy then manoeuvred alongside Magne, providing a carley float containing a leading seaman and the ship’s doctor, before commencing a search for possible U-boat.

What follows is a view of proceedings from the perspective of Wivern in Lt. (later Rear Admiral) Anderson’s post-war book ‘Seagulls in my Belfry’. The account starts following the sinking of Magne:

“Wivern turned into a beautiful circle of foaming water, white against the blue sea, and raced back to the sinking ship to use her for a datum point for the search. Luckily, experience in the Atlantic had made correct action almost second nature. One did not even think before automatically starting the requisite search. As I did so the lookout reported another ship approaching up the swept channel from the Southward. It was the South African ‘Loch’ class frigate, Natal.

Never had I been so thankful to see another ship. Not only did the hunt require a minimum of two A/S vessels, but I had a feeling in my bones that I knew where the U-boat was, that it was in the other half of the search area, which by the book, I should not reach for some time. And here, au moment critique, was a beautiful brand-new anti-submarine frigate with all the latest ASDICs and even better, the new wonder weapon – an A/S mortar known as Squid which was supposed to be really lethal. I told Natal what had happened and gave her the position to start her search”

As matters transpired the South African frigate, Natal, had just left the Tyne on a working up patrol that would take her to Scapa Flow. Sheaf Crown‘s U-boat warning had been intercepted as Natal drew level with the Farnes.

Account of HMAS Natal (Lt. Cdr. D. Hall DSC, SANF. (V) 14th March 1945:

“I was proceeding independently from Newcastle to Methil at speed 12k with twin foxers streamed. This was the ships first voyage since commissioning on 12th March. At 13:25 the southbound SS Sheaf Crown reported a merchant ship sunk (SS Magne of FS 1756) just astern of her and about 5 miles ahead of me. I immediately ordered ‘defence stations’ to be piped. HMS Wyvern [sic] steaming in the vicinity reported that she was carrying out a search and picking up survivors and requested me to assist by carrying out a square search of four miles using the raft’s datum point 55° 52′ N 01°53 W”

Lt. Anderson was Senior Officer for this operation and Lt. Cdr. Hall in Natal was under his direction. Lt. Cdr. Hall again:

“The search was commenced at 13:50. When two miles from the datum point a good echo was reported. This was confirmed by the A/S CO. Use was made of the STU [Short Range Transmission Unit. This indicated that the U-boat was very close to Natal at this stage] which gave a short sharp echo with a straight trace…the plot indicated that the submarine was approaching at slow speed. During the last stages of the attack (six squids set for 120ft at 14:21) the submarine seemed to take avoiding action by turning to starboard, which was not confirmed by the recorder trace. As it was this rating’s first attempt at recording, I think he was unable to keep up with the information supplied by the A/S cabinet.

After the first attack a large amount of oil came to the surface. Officers and engine room personnel said it smelled of diesel oil. In addition a heavy cylindrical tank came to the surface and was later recovered. It appeared to be made of pre-fabricated steel of sturdy structure. When opened a pair of leather bellows was visible inside and these commenced to start pumping (it was of course a dinghy container). The ship’s doctor applied his stethoscope and as no ticking was heard, it was presumed safe to keep it.

Contact was regained at extreme range and classified as ‘submarine’. During the run in on the second attack (6 squids set for 120ft at 14:38hrs) the submarine appeared to be zig-zagging at slow speed towards. The second attack brought up much oil and a much smaller metal tank, which later sank. During the third run HMS Wyvern came up in support but was unable to gain contact. After the fourth run when I lost contact, HMS Wyvern dropped a marker in the position of the second attack while I recovered the wreckage which had been brought to the surface during my first attack”

Natal‘s attack commenced at 14:11 on a contact in position 55° 57 2′ N. 01° 57’W. Wivern remained in the area.

Now we return to Lt. Anderson’s account which picks up at the point of Natal‘s attack:

“Natal altered her course and sure enough, gained almost immediate contact. A few minutes later we saw the Squid missiles arch through the sky and the sea reared up through the heavy explosions.

There followed the short anxious wait to see what, if anything, came up. A large amount of wreckage, or best of all, bodies live or dead were what we hoped for. A little oil, or only some wreckage, was no good. We had learned that such misleading debris could be ejected from a U-boat as it escaped. More was required to be sure of a kill. 

In fact, a little did appear but certainly not enough to prove success. The sea resumed its calm, untroubled blue and I prepared for a long hunt. There were two of us, one a superbly equipped ship, and I had no need to run after the convoy. We might well get him. 

However, the South African had other ideas. He was only on his way to Scapa Flow to work up, but apparently, he thought it more important to keep to his schedule than to help sink a U-boat. Explaining his unusual idea of priorities, he wished me luck and left Wivern to it.

Rosyth in the meantime, was humming like a disturbed bee hive. Every conceivable ship was ordered to sea forthwith to join the hunt for the intruder. This was one U-boat which, on our very doorstep, must be destroyed. I continued the search without much hope. If we had both lost him after our first attack, Wivern alone was not likely to find him again, and it would be hours before we got the support so urgently needed. 
The long afternoon and evening passed and the light began to fade. We were ten miles away from the position of Natal’s attack and still searching. Then as dark crept over the sea we saw it – a long slick of diesel oil staining the calm water. 

Steaming up, I investigated all round the source, but never an echo could Wivern’s elderly ASDIC pick up. However, the U-boat must be there, and its position was clearly marked. I hauled off and came back, steaming right to the centre of the slick. Getting to the end I plastered the position with depth charges. Then I did it again and again”.

At 18:29 contact was regained and a five charge depth charge pattern followed at 19:00.

“When we had spent all of our twenty-five depth charges, we had still brought up no wreckage, but the oil was coming up thick, sluggish and hard. It was obvious that the U-boat would not be leaving. By now all available ships from Rosyth were just over the horizon and, with no depth charges left, it was time to think of rejoining the convoy. Fixing the position exactly to Berwick Lighthouse, which had been clearly visible all day, I reported the situation and left…
Wivern remained in the locality until 20:22 when C.in C. Rosyth ordered her departure South.

On arrival at Sheerness I got down to the detailed analysis of the action. A specialist Officer from C-in- C Nore’s staff kindly came and helped and, between us a few hours work produced a text book Report of Proceedings, complete with sketch maps and narrative of the operation of both ships. It was obvious that Natal’s initial attack had damaged the U-boat, but it had still managed to withdraw at about three knots and, left in peace, Schwebke would presumably have surfaced after dark and withdrawn to seawards and safety. However, the damage, though it produced no visible oil at the time, had eventually resulted in the tell-tale slick which had given away its hiding place, ten miles from the original attack and thus offered us the chance which our primitive ping would have otherwise denied us. Although Natal’s sense of priorities may have seemed odd, his Squid had certainly handed us the U-boat on a plate. 

We carried out the usual convoy cycle via the Humber, had an extremely successful brush with some E-boats, and returned to Rosyth to find ourselves heroes. It turned out that none of the ships that turned out from the Forth had found anything. Darkness had fallen by the time they arrived on the scene and the oil slick had disappeared in the night. With equally old and useless ASDICs, they had picked up no contact and, after searching all night, they returned to harbour. With the lack of hard evidence, this left an obvious doubt in the minds of the Admiralty as to whether the U-boat had been destroyed

The experts in London were only too aware of how important it was to make sure that Donitz was discouraged in this particular gambit. They guessed that success would produce a plague of U-boat attacks on the East Coast which was simply not geared up to meet. A hunter killer group had therefore been sent from Scapa Flow to investigate. These highly skilled specialists had no difficulty in finding the U-boat in the exact position I had reported and, three days after Wivern had left, they blasted the wreck open and gained all the evidence needed to prove destruction. Because no living U-boat could remain submerged for three days, Wivern had been credited with the kill.

Messages of congratulations poured in. Our gin bills quintupled overnight. Nobody, ourselves included, could get over the fact that an old V&W from Rosyth had sunk a U-boat. It was if a pedestrian had run over a car”

On March 18 HMS Ascension with units drawn from Escort Group 17 carried out a tin opener attack at the location of the U-boat contacts. This onslaught eventually brought the following to the surface; wooden gratings, locker doors, an ornamental submarine badge, a Baedecker guide to Paris and three bags of condoms with instructions for use in German. There was now no doubt that a U-boat had been destroyed but what was its identity and which warship had destroyed it ?

It was initially thought by British naval intelligence that the victim had been U-766 as this boat was erroneously believed to have been operating off the East coast. There was a shock in store for Lt. Anderson too;

“We sailed for another convoy, came back – and found that we had been sold down the river. It appeared, unbelievably, that the First Sea Lord didn’t like South Africans and his staff thought it would only be politically desirable but useful with their master if the story could read that a South African frigate un-worked up, had casually destroyed the U-boat in passing. Natal had put in no proper records because she lacked the bridge organisation to do so. Mine, so comprehensively and carefully produced, had been suppressed and replaced by an imaginative if inaccurate narrative concocted in Rosyth. All the signals and letters of congratulations from C. in C. downwards were forgotten and Natal was given the sole credit for the kill. As a result, Roskill’s ‘War at Sea’, based on Admiralty records, and the Confidential Book listing U-boat actions and the ships that were present at the scene, show U-714 as being sunk by Natal alone with no other ship’s in company. 

Under the circumstances, it is not remarkable that Natal collected two DSC’s two DSM’s and five Mention in Despatches. What is surprising is that Wivern actually earned three Mention in Despatches for her success in an action in which, officially, she never took part!”

So, the accusation is that a cynical act of political expediency designed to bolster the infant South African Navy, robbed the crew of Wivern of a successful U-boat kill. The U-boat, which had apparently escaped damage by Natal‘s attack had been irrefutably destroyed by Wivern, according to this view. Rear Admiral Anderson saw his Wivern‘s achievement written out of the history books in favour of the new kid on the block, Natal.
Arguably he had reason to be bitter but his account is factually suspect. According to Anderson’s post war memoir, after some debris had been produced Natal ‘wished Wivern luck and left us to it’ at this point‘. Wivern‘s own Report of Proceedings records that at 18:29 Natal was ordered by Wivern to ‘sweep up close to coast on completion of Box [search]’. Indeed Wivern later sent a signal to Rosyth that Natal was proceeding from the search as late as 20:07. “Wivern to C. in C. Rosyth: ‘Lost contact. Considerably more oil in position since attack. Carrying out Observant. Natal proceeding” Wivern herself was ordered from the scene at 20:22 it will be recalled. Anderson’s account is biased and must therefore be viewed through a prism of literary licence. This does not however make Natal’s claim any more credible.

In order to probe the veracity of the claim further, it is necessary to examine Natal‘s attack in more detail. Natal had been fitted with the latest ASDIC equipment (set 147B with ‘Sword’ scanning attachment to detect contact depth) however the report ADM 199/203 p 392-393 states, ‘Little reliance’ could be placed on her depth-prediction 147B recorder since ‘the tuning was unsatisfactory even after adjustments had been made before leaving Newcastle and the operator was inexperienced’. It was later found that a condenser in the recorder tuning panel had become detached.
It seemed incredible that a ship such as Natal, newly commissioned, operating with an A/S team which was ‘chosen after a period of four days operating under a mobile unit’, could destroy a U-boat in her first ever attack under these circumstances.

Natal made two attacks consisting of six Squid each but two more attacks were aborted before contact was finally lost. The initial attacks produced oil and interestingly, wreckage. Rear Admiral Anderson had felt that, ‘more was required to be sure of a kill’ since just ‘such misleading debris could be ejected from a U-boat as it escaped’. Natal’s attacks had produced a life raft canister, oil said to smell strongly of diesel and a small metal tank which sank before it could be recovered. Wivern’s evening attack by contrast only produced ‘a large circle of oil‘ although earlier in the day Anderson had desired ‘a large amount of wreckage to substantiate a ‘kill‘. Although it was not realised at the time, the life raft canister was evidence that the U-boat had likely suffered fatal damage. Such canisters were fitted between the casing and the pressure hull and any force capable of forcing one and quite possibly two of these canisters away from the void between the two, would likely rupture the pressure hull in the course of releasing them.

The pendulum now swings back in favour of HMS Natal having been responsible for sinking U-714 in the first two attacks. Lt. Anderson’s description of this oil, ‘coming up ‘thick, sluggish and hard’ is consistent with an issue furnace oil rather than the diesel oil used by U-boats.
If U-714 had been destroyed by one of Natal‘s attacks, what had Wivern been attacking that afternoon ? Two miles West from the wreck of U-714 lies HMT Cramond Island, a boom defence vessel sunk by the Luftwaffe on April 2, 1941. The location of Wivern‘s depth charge attacks (55° 52 N 01° 58 W) is also perilously close to the position of the wreck of Magne at 55° 52 N 01° 59′ W.

The definitive evidence that Natal and not Wivern sank U-714 is the position of the wreck at 55° 52 32′ N 01° 59 04’W exactly where the Frigate carried out her attack. The bows are aligned to the South West. The wreck was rediscovered and identified by local divers in 2006 who filmed the wreck (see above). Identity of the wreck was re-confirmed by Dr. Innes McCartney in 2007.

When first dived the boat was broken into three parts and leaning with a thirty degree list to starboard. All crew and torpedo loading hatches were open or torn away. It is likely that this was caused firstly by 17 Escort Group’s ‘can opener’ attacks then by fishing boats in the post war years. It is not possible to state whether the broken pressure hull is due to Natal‘s Squid attack or the subsequent pulverising by 17 Escort Group.
All decking and casing has gone and the wreck is fast deteriorating. The runner rails used to guide the torpedoes into position were formerly visible through the holes in the fore-ends pressure hull. The hydroplanes are set for eternity in the neutral position. After all, U-714 was cornered in shallow coastal water. There was really nowhere to dive.

The conning tower was still in place but hung with filament nets. The tower platform has disintegrated and fallen to the sea bed. The RDF loop and bridge equipment included, some instruments have been carried off by sports divers. The attack periscope is in the housed position suggesting that U-714 was indeed engaged in evasion manoeuvres at the time of the mortar strike.

The Schnorchel mast lies in the retracted position still in the deck slot.
Schwebcke would have ordered it to be lowered prior to making his attack on the convoy. The Schnorchel head is detached from the shaft and lies a meter forward on the port side of the forward torpedo loading hatch. Until recently the Schnorchel head had preserved elements of the Tarnematte coating applied to provide protection from radar equipment. This has disappeared over time. The Wintergarten has collapsed, taking with it the anti aircraft guns. Until recently the guns could be spotted in the murk with their barrels buried in the sand but further collapse has covered all but the mountings. Interestingly a life-raft container is still visible and appears to have been fixed on or adjacent to the gun platforms. For many years the remains of a yellow life raft was visible within the canister.

As for the stern, both propellers are or were in place. The tilt to starboard has forced the two rudders together into a ‘vee’. The divers who found the wreck in 2006 detected evidence of Squid mortar damage to the stern.

In conclusion the evidence is irrefutable that HMS Natal and not HMS Wivern sank U-714 – but it is equally certain that Natal would not have been able to achieve this without the accurate contact position information provided by Wivern at 13:50. As for the unfortunate conscript crew of U-714, their young lives had been profligately thrown away by Donitz and his staff in pursuit of a doomed inshore campaign. Thinking of this episode I am reminded of the closing words of Monsarrat’s ‘The Cruel Sea’;

‘This was 1945. The U-boats had had their battle. Though for all the good it had done them, they might have saved themselves the trouble and spared many fine ships and good men’

Crewmen lost with U-714:

APPENDIX

HMS Natal

Type: Loch Class Patrol Frigate  Yard No: 1788
Built: Swan Hunter, Neptune Yard  Keel Laid: 18.10.43 Completed: 8.3.45

Dimensions: 1435disp – 2260 disp, 286.0 x 38.5 x 8.75(draft)ft
Engines: 2 x Steam turbines, Parsons type, SR geared
Engines by: Wallsend Slipway & Engineering Co Ltd
Propulsion: 2 x Screws, 20.5 knots
Armament: 1 x 4.0ins QF, 1 x 4 x 2pdr AA, 2 x 2 x 40mm AA, 8 x 1 x 20mm guns;   2 x 3 x Squid anti-submarine mortar; 2 x depth charge throwers
Launched: 19/06/1944: as Loch Cree  Transferred to the South African Navy 1/3/45

ASDIC is pivotal to this story. The name derived from Anti Submarine Detection Investigation Committee. ASDIC was a name for underwater-acoustic detection equipment. In effect an instrument which transmitted an acoustic pulse in water and measured distances in terms of the time for the echo of the pulse to return, used to detect submarines. The American term is SONAR.

Basically ADSIC was a submarine detection device housed in a dome under the hull of an anti-submarine vessel or submarine. In active mode it transmitted a narrow beam of sound in the form of a series of impulses, which produced a ‘ping’ or echo from any solid object detected within a maximum range of 3,000 yards from the transmitter. The signal thus produced could enable a skilled operator to deduce the accurate range and bearing of a U-boat. ASDIC could also be used passively in hydrophone mode to detect propeller noise. In this mode it could detect bearing but not range. ASDIC could be baffled by the sound of rushing water (if hunting ship steamed at more than 18 knots), differing water densities, by wrecks, a rocky seabed and by shrimps making their habitual clicking noise.

ASDIC set 144-5Q consisted of a range recorder, providing an echo plot (including a bearing recorder) plus details of speed and course to be followed.

Set 147B consisted of: A depth oscillator. A depth recorder aligned to an automatic depth plotter. 144-5 Q was basically used for obtaining initial contact, determining course to steer then time to fire. The Loch class frigates were fitted with set 147B which under favourable circumstances could detect the depth of the target. The Depth Charge Pattern Control System delivered the coup de grace by means of an automatic firing of projectiles.

U-714

Type: VIIC ocean-going attack boat. Builders: H.C. Stülcken Sohn, Hamburg for Kriegsmarine. Ordered: on 7 December 1940, within the batch of U-711 – U-714. Keel laid: as Yard No.780 on 29 December 1941. Launched: on 12 November 1942.

Commissioned: Oblt.z.S. Hans-Joachim Schwebcke on 10 February 1943.Feldpost No: M 50 495.Technical specifications Hans-Joachim Schwebcke was born in Lübeck on 22 March 1918 and commenced his Naval career in 1937. Schwebcke was Group Officer Naval College Flensburg-Mürwik between May and July 1941 and began U-boat training in January 1942. Schwebcke started his commander’s course with 24th U-Flottille from November 1942.

Armament

Torpedoes

The VIIC boat was designed with five torpedo tubes, four at the bow and one at the stern.

Initially fourteen torpedoes were carried until summer 1943. with two of them in the upper-deck reserve containers. These were later removed to save weight and because it became too dangerous to reload them in North Atlantic waters. In 1944 the number was reduced to ten to increase living conditions in the tube space for prolonged submersion. From autumn 1944 onward, on boats operating i British coastal waters, the ten torpedoes usually consisted of five T5 and five LuT, often stowed as follows:
T5: one in forward tube, three in forward bilges and one in aft tube. Five LuT stowed: three in forward tube, one in forward bilges and one in the aft bilges.

Guns

The deck gun was removed in the Summer 1943. The single gun bandstand aft of the bridge (model 0) was modified that same year by adding a second, lower bandstand with another single 20mm gun (this was then called conning tower modification II). From May 1943, modification IV was introduced, fitted initially with two single 20mm mounts on the widened upper bandstand and a quadruple 20mm mount on the enlarged lower bandstand. After 20mm twin mounts became available in July 1943, twin mounts replaced the single mounts. From October 1943 onward, the 37mm mount replaced the quadruple mounts. This represented the final variation of the Type IV conning tower modification. Later in the war 37mm twin mounts were tested experimentally on a few boats, but the schnorchel had already reduced the threat from aircraft, by then.

Diving depths

The operational diving depth of a VIIC boat was 100m (328ft), with a maximum depth 165m (541.33ft) and a crush depth of 200m (656ft). A crash-dive to 20m took 30 seconds on average

Complement

Both VIIC and VIIC/41 boats carried between forty-four and fifty-two crewmen. With increased AA-armament in 1943/44, crew numbers were at their highest. Following the introduction of the Schnorchel the crews were often reduced to between forty-six and fifty crewmen.
Each Type VII U-boat carried thirty-six unteroffiziere and ratings, generally two unteroffiziere to every three ratings. Apart from the officers, the crew of a U-boat was divided between technical personnel and seamen. The technical division comprised of specialist personnel: diesel machinists, electricians, radio operators and torpedo mechanics. There were four senior NCOs.

Movements

U -714 was assigned to 5.U-Flottille at Kiel as Ausbildungsboot (boat undergoing training) on 10th February until 31st July 1943, with Schwebcke the commander from 10 February 1943. The boat and commander then formally transferred to 7.U-Flottille at St. Nazaire in France as a front line boat on 1st August 1943.

(1) U-714 left Kiel on 23 September 1943 and sailed to Trondheim where she arrived on 29 September 1943.

(2) On 13 October 1943 U- 714 left Trondheim for operations in the North Atlantic.  Here she joined the Körner wolfpack, east of Newfoundland. The pack searched for convoys without success, and with Jahn wolfpack, broke into smaller sub-groups and searched for Eastbound convoys. U -714 later linked up with the Schill 3 patrol line. During the night of 23/24 November, U- 648 was detected by convoy escorts and sunk, while allied ships using depth charges, hunted for U -714 and U- 424 before they made their escape. U- 714 put into Lorient on 2 December 1943.

(3) The boat left Lorient on 11 January 1944 and returned on 15 January 1944.

(4) U-714 departed Lorient on 20 January 1944 and sailed into for the North Atlantic to link up with Igel I wolfpack, west of Ireland. From February 4th the pack operated singly southeast of Iceland. On 11 February, U -714 took the crew of U- 545 on board after their boat was scuttled north of Rockall. Allied aircraft had attacked and badly damaged U-545, the day before. U- 714 put into St. Nazaire on 25 February 1944.Hans-Joachim Schwebcke was promoted to Kapitänleutnant on 1 June 1944,

(5) On 6 June 1944 U -714 left St. Nazaire and sailed with eighteen other non-Schnorchel boats to the Bay of Biscay to form a line between Brest and Bordeaux. When no invasion came by June, U- 714 sailed to La Pallice, arriving on 15 June 1944.

(6) U -714 left La Pallice on 21 August, but returned to port on the 25th, because of mechanical problems.

(7) During her time in port the boat was fitted with Schnorchel and left harbour on 27 August 1944. U -714 headed for British coastal waters and is known to have carried out a patrol in the Bristol Channel in early September, Schwebcke then sailed the boat to Farsund, in southern Norway arriving there on 20 October 1944.

(8) U- 714 departed Farsund on 23 October and sailed to Flensburg where she arrived on 28th. Oblt. Wolfgang Weidenhammer, a crewman of U-714, committed suicide on November 8th 1944, while in Flensburg. On November 11th, U-714 formally transferred to 33.U-Flottille, Flensburg for frontline duties.

(9) The boat sailed from Flensburg on 17 February 1945 and arrived at Horten, near Oslo on the 22nd. The boat came under attack at least once from Allied aircraft, sustaining damage.

ADM 199/1786, ADM 199/203, AUD 524/45 No 64, ADM 199/1013 for p 458

‘Eyewitness: ‘The Ship that never Was’, Warship World, Vol 6, Number 8, Maritime Books 1998, p24 Rear Admiral C.C. Anderson