K-Verbände Attacks against D-Day shipping I

The long-awaited Allied hammer-blow fell on Normandy’s sweeping coastline on 6 June 1944. There the ‘second front’ – a somewhat ironic term considering the bloody battles in Italy that had been raging since 1943 – was opened against the Atlantic Wall and Germany’s days as master of Europe were numbered.

All of the K-Verbände units to be deployed to France came under the jurisdiction of K.z.S. Friedrich Böhme who had been designated as Chief of Kommando Stab West during June. Böhme had had an interesting career, volunteering for the navy in 1916 and holding the appointment of instructor of heavy anti-aircraft weaponry at the Kriegsmarine artillery school in Swinemünde when war with Poland broke out on 1 September 1939. Given command of the destroyer Anton Schmidt that same month, he took part in the invasion of Norway in April 1940. In the course of the battle for Narvik his destroyer was torpedoed and sunk and Böhme, like hundreds of his comrades, found themselves ashore taking part in the fierce battle on land, Böhme acting as supply officer. After the German triumph in the Arctic port he was appointed Seekommandant Narvik, before reverting to command of the destroyer Z23 in August 1940. In May 1942 he served a year as naval liaison to Luftflotte 5 in Oslo, then transferring back to Swinemünde as commander of the artillery school at which he had been during 1939.

On 2 June 1944 Böhme was posted to Timmendorfer Strand to join the K-Verbände, appointed director of operations for 361, 362 and 363 K-Flotillas. As such he became operational commander of the K-Verbände in the Seine Bay, his headquarters situated in Villers-sur-Mer, 10km west of Trouville. The first units of the K-Verbände began arriving on the French Channel coast during the latter half of June as fighting raged amongst the bocage of Normandy. Attempted intervention by conventional U-boats of the Allied invasion fleet had resulted in spectacular failure as the near-obsolete Type VIICs succumbed to the saturating effect of Allied naval and air power. With his S-boats, torpedo boats and destroyers similarly doomed Dönitz turned to the only other weapons in his dwindling arsenal that may be able to have an effect, though he appeared to not have the same dubious faith that his commander in chief possessed:

‘Admiral Dönitz mentioned… difficulties when reporting to Hitler on 29 June 1944. At that time the Negers … were due shortly to begin operations on the invasion front.

‘We shall be able to start operations with the first explosive motor-boats soon as well,’ Dönitz said. ‘But all these weapons are naturally very dependent on the weather.’

Hitler was obviously unperturbed by this reservation. His hopes were high. ‘Of course,’ he declared, ‘the enemy warships – particularly the battleships – must be attacked, just as the merchant ships are. Just imagine it: if England were to lose six to eight battleships in the Seine estuary, the strategic consequences would be enormous.’

Dönitz looked at Hitler, aghast. Did he really believe you could sink battleships with one-man torpedoes? And six or eight of them!

The arrival in Normandy of the sixty Negers that comprised 361 K-Flotilla was accomplished by transport on an increasingly beleaguered railway system. With frequent targeting by Allied bombers much of the journey was made by road in ninety-two trucks from Rudolstadt in Thüringen, via Paris, and finally reaching Normandy where the first thirty Negers arrived at Trouville on the early afternoon of 28 June. From there they were moved to their operational base at Villers, the cumbersome trailers and their cargo hidden amidst the trees of Favrol Wood while the pilots were accommodated in a nearby Norman chateau. During transit by road the trailers and trucks had their naval licence plates blacked out, the carried equipment covered and camouflaged. Any identifying flotilla emblems were removed and the Kriegsmarine men exchanged their uniforms for standard Wehrmacht army uniforms.

A second batch of Negers arrived at the forest on 6 July after reaching their temporary base at Pont l’Eveque the previous day. However, their journey – like their predecessors’ – had been frequently disrupted by Allied fighter-bombers who exercised almost complete dominance of the skies over France. Little movement could be attempted by daylight lest the swarms of sharp-eyed pilots discovered them and strafed the convoy below. It was during one such attack on 30 June that Krieg himself was seriously wounded, his place taken as flotilla leader by Fähnrich Potthast who compensated for his lack of rank with experience aboard the Negers. Twelve Waffen SS volunteers also augmented the unit; men from Otto Skorzeny’s newly formed SS-Jagdverbände of hardened adventurers.

Indeed the K-Verbände remains the only Kriegsmarine unit to have admitted SS members knowingly into its ranks. However, this knowledge was not open to all. In June 1944 Böhme discovered this for the first time as is evidenced in his POW interrogation after the war’s end:

The presence of SS men amongst the fighting personnel of K-Verbände units first came to light in June 1944 when Böhme accompanied a party of eight men to Berlin to receive decorations. During the proceedings Skorzeny appeared and admitted that four of the men were members of the SS.

Böhme was subsequently informed by Admiral Heye that an arrangement had been made between himself and Skorzeny in May 1944 whereby K-Verbände would absorb SS men under sentence who would be willing to undertake suicidal actions (Totaleinsatz) on a voluntary basis as a form of probation.

The flotillas in KdK subsequently received a number of SS men from the Lehrkommandos without knowing their real origin

It is unclear how many SS men served in the K-Verbände and to which units they were definitely attached. At least twelve Waffen SS men are known to have joined 361 K-Flotilla, eight each in 362 and 363, six in 611, eight in MEK 80 and ten in Lehrkommando 700. Whether the SS volunteers were truly of a probationary nature or rather motivated by the high esprit de corps that marked Skorzeny’s unit can only be surmised, certainly the above text suggests the former, while knowledge of the SS commando unit’s actions during the war reflects the latter.

However, the Neger was not the only part of the K-Verbände to be deployed. A single Biber had also been shipped from Kiel via Aachen, Paris and Rouen for an attack against British-held bridges on the Caen Canal and Orne River. As we shall see later the proposed mission was aborted before the Biber could be deployed. As in Italy, it was the Linsen that would be first deployed in action.

After the absorption of the Brandenburg Regiment’s Küstenjäger battalion into the Kriegsmarine following their disappointing performance in explosive motorboats off Anzio, the initial cadre of the K-Verbände’s Lehrkommando 200 had been established in June 1944 on the south bank of the River Trave between Lübeck and Travemünde. Named ‘Blaukoppel’ the base hosted Kaptlt. Kolbe who commanded the training unit for the prospective Linsen pilots and crew. Among the fifty permanent staff of the Lehrkommando (at least twenty of them ex-Brandenburgers) was Obit. Taddey, a wireless expert, his experience crucial for the operation of the remote-controlled explosive Linsen. A small ancillary Linsen training centre was also established on Lake Müritz, named ‘Grünkoppel’ and comprising around 100 men and six Linsens.

While the initial batch of Linsens used by the K-Verbände was of Brandenburger origin, the Kriegsmarine had swiftly set about designing and constructing their own boats in a crash-building programme. The theory behind the units’ structure and operation was simple. Each Linsen combat unit (called a Rotte) would comprise a control vessel and two explosive craft (the group controlled by the group leader, or Rottenführer). The control boat carried three men, a pilot and two radiomen, one each to control the remotely-operated explosive boats. These carried a single pilot who would bail out of the craft when it was set on the correct path and be (hopefully) picked up by the control boat afterward.

The Linsens built for the K-Verbände measured 5.75m in length (25cm longer than the Brandenburg design) with a beam of 1.75m (5cm slimmer). The height of the craft measured only 80cm making it a small radar profile at best. The total displacement was a maximum of 1.85 tons. Beneath the engine cover amidships was a 3.6-litre, 95-horsepower Ford V8 ‘Otto’ engine that could push the boat at a speed up to a maximum rated 33 knots, though the 100 nautical mile radius of action was calculated for 15 knots. Two 5-litre containers held enough fluid to lay a smokescreen in action as the explosive boats hurtled towards their enemy carrying a charge of 300–400kg of explosives in the stern. Fitted around the bow of each explosive boat was a metal framework that was held 15cm away from the gunwale by spiral springs. If a pressure exceeding 80kg was exerted on these springs the metal framework would be forced against the gunwale closing a circuit that ignited a small charge in the bow. Blowing the bow off, this would enable the craft to sink while also starting a delay fuse to the main charge in the stern that was preset to between two and seven seconds. In theory this allowed the remains of the boat to sink beside the target ship where its subsequent detonation would cause the maximum damage.

In practice the three-boat unit would approach the enemy using stealth, until the explosive boats were close enough to begin their attack run. At the appropriate moment the two explosive boats would be accelerated to maximum speed and begin their attack. The pilots would make whatever adjustments were necessary before turning on two navigation lights visible only from astern, switching the controls to radio-control and throwing themselves overboard. In the control boat the radio operator used a small box that he cradled on his knee to control the now-pilotless explosive craft. There were six settings for the lever: starboard, port, stop engine, start engine, slow ahead and accelerate. The final control was a firing switch. The radio control equipment was much the same as that which had been developed by the Army for use in the ‘Goliath’ remote-control demolition charge carrier. By keeping the two navigation lights – one green towards the bow and a red stern light – in a vertical column, the operator knew that the boat was heading in a straight line towards the intended target. Production of the improved Linsen began at the end of May 1944 in Königsberg’s Empacher & Kalisch boat builders, soon farmed out to firms throughout Germany.

Kaptlt. Ulrich Kolbe’s Lehrkommando 200 despatched Linsens of Obit. Helmut Plikat’s 211 K-Flotilla from Germany on the day of the invasion, the unit arriving at Bolbec east of Le Havre on 19 June accompanied on their maiden posting by Kolbe himself. The entire flotilla numbered around 250 men, including the support staff commanded by flotilla engineer Lt (Ing.) Max Becker. The pilots were quartered in a luxurious villa that belonged to the Rothschild family at Molitor. The cutting edge of the unit numbered twenty-four Linsens, though the accompanying communications, armaments, transport and other logistical units (including a small flak detachment) considerably swelled its ranks. From Molitor they moved during the ensuing two days forward to Honfleur, which would be their operational base and from where they initiated operations.

The German K-Verbände faced a well-prepared and dauntingly massive enemy that was ready to face the novel German weapons all across the invasion front, as evidenced in this US Navy appreciation of Allied naval dispositions and the foe they faced:

Enemy naval forces within the Channel consisted of an indeterminate number of human torpedoes, self-exploding pilotless surface craft, sea mines to be laid by aircraft, and … 195 miscellaneous vessels.

To repel these enemy forces, the Task Force Commanders established an area screen … Manning the area screen required a careful phasing in the use of vessels. Until Allied forces arrived in the assault area, there was no screen. On arrival, a proportion of the escorts and patrol vessels took up screening patrols. Still later, other vessels, which had completed their initial tasks of boat control, close fire support, or some other job, took over patrol duties, while a proportion of the escorts returned to the UK in company with the convoys.

B. Eastern Task Force … [that bore the brunt of K-Verbände attacks]. The system of defence employed in the eastern area was the following: constant patrols to seaward by corvettes, trawlers and sometimes destroyers were carried out.

Every 24 hours one division of four destroyers was detailed as duty division for the entire area while two other destroyers were detailed as guard for areas O and J. By day, these destroyers performed such other tasks as were assigned, but they were subject to call in case an attack threatened. By night they were posted as directed by Captain (Patrols). In neither case did they actively patrol up and down the defence line. The plan was that Captain Patrols would vector them against enemy forces, whose presence was discovered by radar or other means.

During the hours of darkness or low visibility, this defence was augmented by a line of minesweepers anchored 5 cables apart along a defence line parallel to the shore and six miles to seaward.

This defence line was continued down the eastern flank by a line called the ‘Trout’ line, composed of LCGs and LCFs, anchored 1 cable apart. The duty of the minesweepers and Landing Craft on this defence line was to prevent all enemy ships and craft from entering the British Assault Area, to illuminate the outer areas when ordered and to counter attack any submarine detected.

Two or three divisions of MTBs were stationed, stopped but under way, to the Northeastward of the N.E. portion of the defence line; two or three sub-divisions of destroyers were stationed on patrol, to the north of the western half of the area, and sometimes to the northward of the MTBs; other light forces were stationed close inside the defence line, to act as reinforcements or as ‘pouncers’. BYMS and MMS were anchored as mine spotters, originally in the approach channels, but later in the lateral swept channel established within the area.

These defences were augmented by a smoke screen laid by specially fitted craft at dawn, dusk, and as required.

The enemy’s day activity was limited to one long-range torpedo attack, by torpedo boats from Le Havre, at 04.50 on D-Day … By night the enemy’s attack was more determined. On four occasions he operated torpedo boats, and on eight occasions E and R-boats, in the eastern Task Force area. On every occasion except one these forces were intercepted and forced to retire. In no case was any success obtained by enemy. The line LCG and LCF, anchored on the eastern flank took a heavy toll of the human torpedoes which attacked in July …

The Allies had also gained a huge advantage over the K-Verbände when during May 1944 they had penetrated the Enigma code net in use by Heye’s service. Named Eichendorff, and codenamed ‘Bonito’ by the Allies, the Enigma net had been instigated in March 1944 and was used until the end of the war. Though first broken by the Allies during May it was not until July 1944 that it was considered mastered by Allied cryptanalysts. The sole saving grace for Heye was that he and his commanders rarely mentioned specific areas or timings in their reports. Nonetheless it was a severe handicap, though one of which they were oblivious.

On the evening of 25 June the Linsens were readied for their first mission. Eight control and nine explosive boats were towed to sea by R-Boote of the 4. R-Flotilla (2. Sicherungsdivision). These motor minesweepers had been based in Boulogne-sur-Mer since the fall of France in 1940, their strength gradually eroded by years of insidious mine warfare and the sudden onslaught of Allied power in the prelude to D-Day. However, the remaining captains and crew were familiar with the local waters and several were pressed into service as towing vessels for the small Linsens. Unfortunately for German plans, the pilots of the explosive boats were not so skilled and as R46 eased from port with its tow, bad handling by the Linsen operator caused the little craft to veer wildly while running alongside the minesweeper, nudging the large craft’s hull with enough force to close the detonation circuit and explode it. Both were lost in the blast as well as a further two control Linsens and one explosive Linsen. As the explosions buffeted the remainder many fouled their towlines and in the increasing confusion the operation was scrubbed, the R-Boote and their charges returning to Honfleur the following morning. Two further attempted attacks were launched during June though they too ended in confused failure. Accidental rammings by the inexperienced Linsen operators – resulting in several sinkings and much damage, as well as defective weaponry saw both attempts turn into fiascos until on 30 June Böhme reported to Dönitz that the remaining Linsens of 211 K-Flotilla were no longer serviceable. Their planned deployment was postponed and instead the human torpedoes brought forward into action.

This time there was to be no repeat of the problematic launching suffered at Anzio. Two companies of Wehrmacht pioneers were commandeered and they prepared the landing site by first of all clearing a wide strip of the tangled coastal defences erected by the Germans and clearing a track along two sandspits that were almost completely dry at low water. From these promontories two wooden slipways were also prepared to provide a firm base on which to wheel the human torpedoes into the water. To avoid the unwelcome attention of the RAF the runways were covered in camouflage netting.