Seehunds in the Thames Estuary I

By 29 January 1945 the ice at Ijmuiden had melted enough for the Seehunds to return to action. Likewise in Hellevoetsluis, the Bibers were no longer trapped in port by the thick winter ice and they too were made ready to sail. Ten Seehunds put out through the small lock at Ijmuiden in two groups; one bound for the Dumpton-Margate area and the other for the South Falls. The Seehunds were ordered to break off operations if the weather deteriorated from the southwest, though all ten successfully sailed. The first to return, U-5342, entered port that evening, Obersteuermann Bocher and Obermaschinist Frobel breaking off their journey with clutch failure after only three hours at sea.

Over the following days seven of the Seehunds returned with various mechanical problems or because of the increasingly heavy seas. Some had reached the approximate area of their intended operations, though they had been forced to abort. Leutnant zur See Henry Kretschmer was one of those that returned, bringing U-5041 into port after being battered by the elements. His engineer, Maschinenmaat Karl Radel, had become violently seasick and reached port in a state of almost complete exhaustion.

Only two of the Seehunds successfully patrolled their target areas, L.z.S. Stürzenberger and Obermaschinist Herold aboard U-5335 sighting three steamers and two escorts in convoy, but they were unable to gain a firing position. They soon broke off the mission in mounting seas, reaching Ijmuiden on 31 January. Oblt.z.S. Ross and his LI Oberlt (Ing.) Vennemann reported the sole success after torpedoing an estimated 3,000-ton collier near Dumpton Buoy in Margate Roads on 30 January. The two Germans were elated, though the British reported their steamer sunk by mines. It was the third sinking made by a Seehund since they had been put into service, aggregating an estimated 6,324 tons.

The same day that the Seehunds had sailed, fifteen Bibers set out from the Hook of Holland, having arrived there from Rotterdam the previous day. However, disaster overtook them almost immediately as three were sunk by hitting patches of ice which in places were 20cm thick. Five more returned with damage caused by the ice and another was beached near Hellevoetsluis after spending 64 hours at sea hunting in vain for the sight of any potential targets. The remaining six failed to return at all, their fate unknown.

January ended on this grim note for the K-Verbände, though Heye remained optimistic about the Seehunds at least. In a review of their operations Heye wrote on 4 February that despite their operating in severe weather conditions and meeting little success, they had unquestionably been of great value in eliminating teething problems with the small U-boats and for the training of their crews – at least those that had survived. He also expressed faith in better results once weather conditions moderated.

On 3 February the commander of the Seehunds in Ijmuiden was changed. Kaptlt. Rasch was rotated back to Germany to oversee the operation of Lehrkommando 300 in Neukoppel. His replacement was the celebrated U-boat veteran F.K. Albrecht Brandi, who became the chief of 312 K-Flotilla and later 5 K-Division. By now the threat of the midget submarines was being taken very seriously in British military thinking and on 3 February thirty-six Lancasters of 5 Group attacked concrete shelters at Ijmuiden (9 Squadron) and Poortershaven (617 Squadron) with Tallboy bombs. It was believed by the British that these pens were sheltering the midget submarines and in clear weather the RAF claimed hits on both targets without loss to themselves. Their appraisal had been correct: the S-boat bunkers in the Haringhaven received three direct hits though there was no damage to the Seehunds of which there were four operational and twenty-seven non-operational currently in the port. The bunker was never fully completed after work had begun on it, only ten pens being finished out of a planned eighteen, the Allied bombing achieving little despite its accuracy. On the other hand, the Molch depot was hit with greater result by Spitfires of 2nd Tactical Air Force who were engaged on a general attack against the railway system in the town of Amersfoort. Though no Molchs themselves were damaged the depot was virtually destroyed. Lancasters also attacked the Biber depot at Poortershaven and once again though no submarines were hit, damage to dockside installations prevented any more operations in February. The British were soon back again against the K-Verbände when fifteen Lancasters of 617 Squadron dropped Tallboys again on the pens at Ijmuiden without loss to themselves on 8 February. Of equally great concern was the RAF battering of rail communications between Germany and Holland that threatened to seriously disrupt the supply of Seehunds to the forward area. On 11 February consideration was given to transporting them via road through Zuiderseedamm and employing them within the inner Scheldt. This would negate the effect of bad weather as the inner reaches were relatively sheltered from the harsh elements of the North Sea and plans were developed to attempt a trial Seehund operation within the Scheldt.

In the meantime operations continued against the convoys trailing from England. Eight boats sailed on 5 February; U-5368, U-5033 and U-5326 all returning defective, U-5339 stranding north of the Hook of Holland, U-5311 stranding 14km north of Ijmuiden and U-5329, U-5348 and U-5344 returning without success and with varying degrees of depth charge damage. On the evening of 10 February eight Seehunds sailed, U-5335 forced back to harbour to repair a defect in its steering gear, though it was able to depart the following day. The dockside at Ijmuiden was scarred and still smoking from the attack by nine 8th Air Force B-17 bombers that had carried out the first of what they termed ‘Disney’ missions using Royal Navy rocket-boosted concrete-piercing bombs against the pens at Ijmuiden. Three more Seehunds – U-5363, U-5337 and that belonging to L.z.S. Polakowsi – were forced to return on 11 February with mechanical faults and U-5330 the following day, having sighted Allied ships but achieved nothing. U-5339 entered Vlieland on the evening of 12 February; U-5345 into Ijmuiden and U-5347 grounded on Texel 30km north of the port on the morning of 13 February after suffering severe damage in an air attack. Only U-5349 failed to return from the operation.

A further five departed Ijmuiden at 17.00hrs on 12 February, despatched to the North Foreland. Again two – U-5332 and U-5342 – aborted with mechanical difficulties. Oberfähnrich Streck and Maschinenmaat Niehaus aboard U-5345 reached their operational area, but were detected and subjected to a barrage of depth charges that the Kriegsmarine men counted as numbering 259 detonations before the attackers left the scene. With the boat badly damaged and crew shaken by their ordeal they limped towards Ijmuiden, eventually beaching their boat at the inner mole of the harbour. The fourth Seehund, L.z.S. Götz-Godwin Ziepult and Maschinenmaat Reek’s U-5361, returned on 17 February after claiming to have torpedoed a 5,000-ton merchant ship off North Foreland two days previously. The ship concerned was the Dutch tanker Liseta from convoy TAM80, badly damaged by a torpedo hit although able to reach port without sinking. However, the Seehund was not the only attacker to claim the hit, the Type VIIC U-boat U-245 also claiming to have torpedoed the Dutchman. Nonetheless, it was a victorious crew that reached Ijmuiden. The last of the five, U-5356, never returned.

On 14 February, while many of the Seehunds were still on station, it was decided to slip their leash more and extend operations to anywhere within their range, which included inside the Thames and as far as the Humber estuaries. Hitherto these areas had been off limits for the Seehunds. It was also ordered to stop any K-Verbände mine laying along the Thames-Antwerp convoy route to allow conventional U-boats to begin patrolling there as part of their last-ditch inshore campaign in British waters.

In the meantime a number of Molchs had been moved from Amersfoort to Scheveningen to be used in the Scheldt estuary. Their use was planned for the night of 12 February, but the deteriorating weather forced a postponement. During the night of 14 February two Linsen units were moved from Hellevoetsluis to Zeriksee on Schouwen to operate against Walcheren as the K-Verbände intensified its Scheldt attacks once more. As part of this stepping-up, the trial of the Seehunds in the Scheldt began on 16 February.

Four Seehunds sailed from Ijmuiden for the West Scheldt that morning, five Linsen units also sailing for the region that night. It would be the baptism of fire for the two-man midgets within the confined waterway and one that was ultimately unsuccessful. There was no word from the Seehunds until 20.00hrs on 18 February when U-5363 beached 15km north of Ijmuiden after experiencing no success at all. Another, U-5332, also beached itself, this time 3 kilometres north of the port at the same hour the following day. L.z.S. Wolter had fired two torpedoes after sighting an enemy convoy of several large landing craft but had missed after being kept at bay by the escort screen and unable to launch an attack at a close enough range. The remaining two boats, U-5041 and U-5337, did not return, though Maschinenmaat Karl Radel of U-5041 drifted ashore on the island of Voorne in a rubber dinghy, dying before he could relate his experiences. His coxswain L.z.S. Henry Kretschmer had been captured after a successful depth-charge attack by HMML901 on 22 February. The British motor launch was severely damaged during the battle with U-5041 in which a depth charge set off a sympathetic explosion of the midget’s torpedoes, damaging the ship’s wheelhouse. Five out of six rounds fired from the motor launch hit the Seehund and Kretschmer was soon pulled from the sea, Radel drifting away unseen in the early morning darkness. It was to be the last time that Seehunds were deployed within the Scheldt itself, that zone of control left to the equally unsuccessful Linsens, Bibers and Molchs. The Linsens that had deployed into the western Scheldt on the same day as the Seehunds had achieved no success either. Only two units reached the target area where they found nothing, the rest turning back in thick fog losing two of their number.

Bad weather once more frustrated plans for three Seehunds to sail for the Dumpton area on 19 February, though they were able to put to sea the following day. One returned with engine trouble which took 24 hours before it was rectified and the craft put out once more. Three more put to sea that same day, destined for the Elbow buoy in the South Falls off North Foreland, another single Seehund making for the same area on 23 February. U-5097 returned after a frustrating journey dogged by bad weather and poor visibility. After reaching the area that they considered to be the shipping lane from southeast England to the Scheldt estuary they were surprised by two British MGBs that raced out of a fog bank with machine guns blazing. Crash-diving to the seabed at a depth of only 30m, the two Germans were then subjected to a fierce depth charge bombardment, able to see the flash of the exploding Torpex through the Plexiglas dome. After nearly 24 hours, U-5097’s attackers dispersed and the Seehund was able to creep away toward Ijmuiden, severely damaged. The boat was leaking from the area of the electric motor and its compass had been destroyed, so they were unable to remain submerged, the captain, Wachsmuth, navigating by the constellations of the Great Bear and the Small Bear when they became briefly visible through the cloud. By daylight he used the horizon from which he considered the strongest morning light to emanate, unable to actually see the sun due to the daytime fog. As U-5097 headed for the Dutch coast Wachsmuth was suddenly confronted by a stone wall looming from out of the fog and rapidly threw the boat to port to avoid hitting it. However, in hindsight it appears that the vision was an hallucination brought on by the Pervitin pills that the two Germans were consuming to stay awake. The wall vanished as quickly as it had arrived.

They eventually made landfall as fuel and battery were almost exhausted, though with no idea of their location. In fact they had grounded the Seehund at Egmond aan Zee, 16km north of Ijmuiden and there they blew it up. Wachsmuth and his LI remained unsure of their location until a Wehrmacht soldier appeared. The newcomer was Mongolian and nervously escorted the pair off the beach and into a bunker occupied by Luftwaffe Flak troops. They still had to convince their rescuers that they were not Allied commandos before eventually contacting Brandi by telephone and being returned to Ijmuiden.

U-5342, on its first operational sortie, did not return; the two crewmen listed as missing presumed killed on 1 March 1945. The last crew of the trio, also new to action, did make a successful return to Ijmuiden, though Frohnert and Beltrami had achieved nothing.

L.z.S. Winfried Ragnow’s U-5367 was one of the four-boat group that had departed on 21 February. Ragnow later recounted his departure from Ijmuiden, a scene repeated for all departing Seehunds.

On 21 February my boat was the first of the flotilla to be cleared for patrol. A fortifying breakfast, specially catered – ‘klinker-free’ diet (as our ‘sled’ had nothing like a WC). F.K. Brandi gave our operational briefing 08.00hrs. We learned one more time all the important details about the operations area; currents, weather forecasts, enemy locations and convoy routes for the Thames-Scheldt supply lines, security, defence, air dispositions and so on. Weather wasn’t especially good, but it was supposed to be better in the Thames. Best wishes, a handshake and I was dismissed. Equipment taken by truck to the harbour where the LI is on hand and just as tense as I am about the mission. KUB367 (U-5367) lies at the pier. This time we have sharp torpedoes under her belly (each Eel had 300kg Trinitrotoluol in the head). We smoked a last cigarette, said goodbye to our comrades and support personnel. And then we went. Past the lock gates and outer mole. Windy -sea state 3 – breakers washing over the boat. Trim dive test by the Ijmuiden navigation marker and then course southwest at 6 knots – on towards England!

Despite their stalwart beginning, the two men had no success on their arduous voyage. Alternately hunting surfaced and diving to avoid enemy destroyers, MGBs and aircraft – once making the unprecedented depth of 76m with no untoward problems with their boat -they unsuccessfully attempted to attack a destroyer before heading back towards Holland. They grounded their boat amidst the beach defences, huddling in a bunker and keeping warm with schnapps before found by a Kriegsmarine artillery unit and returned to Ijmuiden. Later, Brandi dispatched a group to find and recover their Seehund, but it had drifted off with the tide and presumably sunk. Ragnow and Paul Vogel were sent to Wilhelmshaven to collect a new boat; both men awarded the Iron Cross Second Class on 28 February, the first of their flotilla to receive the decoration.

The three other Seehunds that had sailed as part of the group led by U-5367 experienced mixed levels of success. L.z.S. Horst Gaffron and his engineer Maschinenmaat Huber fired both torpedoes at an enemy destroyer, reporting a hit though British records do not confirm this. L.z.S. Walter Habel and Maschinenmaat Karl Rettinghausen also reported success. Sailing toward England on their first mission, the boat ran surfaced towards the Thames. The trails of V2 rockets could be seen arcing overhead on their way toward London as the young crew sailed toward their enemy. At 09.00hrs they sighted an enemy destroyer and launched two torpedoes before breaking away as an MGB passed over-head dropping defensive depth charges for twelve hours. They claimed to have hit the destroyer that they identified as HMS ‘Mecki’ – perhaps Mackay – though British records do not confirm this. However, the 1,625-ton tank landing ship LST364 of convoy TAM87 was hit by a torpedo and sunk, the attack attributed to an unidentified Seehund. The 220-strong British crew, of whom twenty-four were burnt and wounded by the detonation, were taken off by the trawler HMT Turquoise. Seehunds were the only active German submarines in that area, though the identity of the successful attacker remains unknown to this day. The last of the group, L.z.S. Hermann and Omasch. Holst’s U-5365 ran aground while returning without encountering the enemy. Stranding in shallow water near the German artillery batteries on Katwijk, Hermann paddled ashore in a small rubber dinghy to report their predicament while Holst remained with the boat. Shortly thereafter a Dutch lifeboat from Ijmuiden arrived with a salvage command on board, the Seehund towed into Scheveningen shortly afterward.

The last sailing of February, L.z.S. Klaus Sparbrodt and Maschinenmaat Günter Jahnke’s U-5330, which had put to sea on 23 February, was more definite in its result. This, the eleventh Seehund operation, was again targeting the Dumpton area, though it suffered its share of problems en route. They had barely reached Scheveningen when the diesel engine failed, forcing a premature return to Ijmuiden on electric motor. The problem was swiftly identified as a blocked oil pipe and soon rectified, the boat putting out once more for action. Attacked by Beaufighter ‘J’ of 254 Squadron as they cruised with battened hatch due to the choppy water, Sparbrodt crash-dived his boat and continued from the scene submerged while the hunter circled the area searching in vain for the Seehund.

By 22.00hrs we were nearing our patrol area. An hour later we were approaching a light-buoy, which told us that we had found the Dover route. Suddenly an unmistakable sound met our ears; the ignition of the engines of two motor gun boats lying in wait between the convoy route and the Goodwins. We dived immediately and lay there at 58 metres until 04.00hrs on 24 February. From then on we surfaced every hour to see how the situation was, but every time when we were at the top we heard the noise of the MGBs and we shot like a stone back into the ‘cellar’. At 07.00hrs the end came and we heard the gunboats heading away, surfacing in time to see them travelling at high speed for Ramsgate.

The sea was mirror-like – sea state 0. We headed at half speed towards Dumpton Buoy that lay in the middle of our operations area … We hoped that here we could find a convoy and fire our torpedoes at some worthwhile targets … A slight haze hung low over the water and we patrolled up and down at low speed. A little after 10.00hrs in a thickened mist I saw what looked like a vessel lying stopped, and we were slowly getting closer to her. At 10.20hrs we dived and began our attack.

I could now see that the ship was a warship, the forepart clearly visible but the rest lost in mist. I saw a long and high forecastle, a menacing cannon, large bridge, mast and funnel that showed it was at least a corvette and worthy of an Eel.

At 10.27hrs, the LI reported port torpedo clear for firing. I studied the target through the periscope. Its bow was facing left, at about 80° from us, and I observed no change as a minute passed. This indicated that it and the Seehund were both set in the same direction by the gentle current.

Estimating the range at 600 metres, after that minute I ordered ‘port torpedo – fire!’ and Jahnke pulled the lever. We heard from the boat’s hull a scream and roar as the Eel sped on its way. I started the stopwatch and put the rudder hard to starboard. I wanted to make a full circle and return to the same attacking position. 50, 60, 70 seconds went by and we heard nothing. The torpedo must have missed, but I was determined to get off a second shot.

Then at last, after 80 seconds following the shot, we heard a sharp crack through the water, but nothing more. This meant that the range had been 850 metres. I saw a column of water and smoke from the explosion rising midway between the bridge and funnel. I shouted, ‘blow tanks’ and within seconds we were on the surface and I called Jahnke to the tower. We saw the last of the ship as her bow lifted high and she quickly slid stern first into the sea.

The two men quickly submerged, celebrating their attack with a meal of chicken and rice followed by some strawberries before ten depth charges from a tardy retaliation reminded them of their precarious situation. They lay on the seabed as the hunt faded away and headed from the scene. Later that night, according to several accounts, they fired their last torpedo at a sighted ship but apparently missed, heading back to Ijmuiden and a victorious welcome. After confirming the details of their attack with Brandi the two Seehund men were informed that they had sunk the 1,505-ton Free French destroyer La Combattante, corroborated by intercepted British radio transmissions. The ‘Hunt’ class destroyer had begun life as HMS Haldon, but had transferred to the Free French Navy in 1942. She had patrolled the English Channel from March 1943 onwards and joined the Normandy landing on 6 June 1944, later conveying General Charles de Gaulle for his first journey to liberated France on 14 June 1944. She took sixty-two men, including two British, down with her. Curiously a torpedo also hit the British Post Office cable-layer steamship Alert east of Ramsgate during the night of 24 February. The 941-ton ship sank so rapidly that it was unable to send a signal reporting its loss, and this has been attributed to U-5330 as well. Could this have been the target that Sparbrodt believed he had missed?

There remain several sinkings often attributed to either mines or Seehund attacks that to this day remain unconfirmed as to what caused their sinking or indeed their exact identity. As well as the mysterious HMS Mackay, LST364 and the cable layer Alert, a Seehund whose number remains unknown reported sinking a ship named ss Rampant from convoy TAC near buoy NF8 off Ostend in the early hours of 26 February according to the eminent historian Jürgen Rohwer. However, despite the other ships apparently rescuing forty-six crewmen, Lloyd’s Register carries no such ship name. Additionally, on 26 February the 4,571-ton British steam tanker ss Auretta was in convoy TAM91 with twelve other merchants and five escorts en route to Antwerp in heavy seas when she was either torpedoed or hit a mine. Likewise the American steamer ss Nashaba was also lost from this convoy to either a mine or torpedo hit, one crewman and the pilot going with her to the seabed.

Harald Sander was engineer aboard one of the Seehunds that was active during February:

Some were actually inside the mouth of the Thames. So the two of us had to go down there. Well, I will never forget those two days and the conditions we experienced. We had a wind speed of 10 or 11 and the swell was correspondingly large … So anyway, we got there all right. The only thing was that then misfortune struck. The diesel air valve stopped working and every time we came up out of the water a wave washed into the boat. Our stern was getting lower and lower in the water and it was almost as though the rear of the boat couldn’t get to the air at all but stayed submerged. At the time I asked my commander, ‘How deep is it here?’ ‘Oh’, he said, ‘we are already quite far down. We are just about in that deep valley that runs from the North Sea through the channel in the direction of Biscay’. And he said, ‘It must be a good fifty metres’. I said, ‘Let it go down’.

At thirty metres the situation normally became quite serious with our boats, but we let it go down and we waited till we got to the sand and then we said, ‘So, now we are down’. One has to consider that we had an atmospheric pressure per square centimetre of five and the thickness of the outer metal around the boat only had a strength of five millimetres. The boat ribs were placed thirty centimetres apart, so it was practically like fishbones … and the body of the boat only had minimal strength.

But it didn’t crack. There was no noise from the boat. The only thing was that water came from astern into the front and we were both sitting in water. Well, the commander was seated a bit higher and I was a bit lower behind him, but we were both sitting in water. First we took a deep breath and then we said, ‘Okay, what shall we do now?’ and then we tried to surface the traditional way. The diesel engine cannot be started under water because it needs air, so we tried it with the electric motor. We put the hydroplane up at the front and then we started the electric motor and revved it up until the boat was high enough to have the nose poking out of the water, so that air came in and I could start the diesel engine. The diesel engine was then used to pump out the diving cells. We were so heavy that there wasn’t much water in the diving cells anyway. I hadn’t flooded them. The boat itself was heavy enough. A ship only floats if it has enough displacement to allow it to remain above the surface. Well, all right, this didn’t work because we were too heavy. We couldn’t pump either because our bilge pump only managed at a depth of 25 metres. It had 2½ times atmospheric pressure and this could be managed with the hand bilge pump. This was possible, although at a depth of 50 metres … We were both still fit and didn’t want to abandon ship. Getting out was not that easy at a depth of 50 metres and it could have been dangerous. So we kept trying.

We had two compressed air tanks in the boat in case of emergency and I released compressed air into the first diving cell in the bow and in this way the boat rose at the front a little. Then I started the electric motor and the boat actually rose up with this pocket of air in the bow. If you can imagine that practically half of the boat was still submerged, then we began pumping. We were pleased that we were at least up on the surface. Then came the question, ‘Are there ships up there?’ Underwater you can hear a long way. You can hear the noise made by every screw. There was nothing. We had waited so long for night time, until it was dark. They didn’t discover us and we began pumping eagerly in order to make the boat lighter so that we could continue on. We knew that the valve was broken. We were of course swaying close to the surface. The air quality inside wasn’t very good which made us both very anxious and we exchanged comments, such as, ‘Come on, do it, keep pumping’, and so on. At some point afterwards, I don’t know when, suddenly the commander said to me, ‘Harry, I can’t go on, I don’t know what’s happening, I’m getting out’, and such things. He was panicking and thinking he wouldn’t make it, but we had to, because if we didn’t keep pumping we would have sunk again and been down on the bottom at 50 metres. For me it was … anyway, I don’t know how I managed it. I yelled at him. I really told him what I thought. I said, ‘If you don’t, I will smack you between the eyes!’. He had to be brought out of his shock. So this was how it was. These days I get asked, ‘How could you have done anything in that small boat?’ The narrowness had an effect in that moment when neither of us were sane.

We managed our work all right but at any moment it could have all gone wrong. The English could have run us over if a boat had been there and if they had discovered us they could have chased us down to the bottom and so on. So I really had to pull myself together. The fact that I managed this is a great thing. I still say today, God had a big hand in it my whole time with the navy. In any case, to cut it short, we managed and we returned home, at least to Ijmuiden. We went on a bit and then we both pumped again and then we went on until we came to the locks. Then we told the lock keeper to adjust the crane after we were through and pick us up with the crane straight away so that we didn’t fall again because the boat was only just floating. That was the best it could do. They weren’t very pleased when we returned, but the main thing was that we were there. Both torpedoes were still attached, so they hadn’t been wasted. It was all valuable material. But, yes, the boat was wrecked.