U-480: The Kriegsmarine’s Stealth Submarine

U-480: The Kriegsmarine’s Stealth Submarine

Although ‘stealth’ is a somewhat modern term applied to certain high-end military machines, U-480 was the first operational U-boat to use technology specifically designed to reduce the possibility of underwater detection by sonar. In August 1944, it went on a seemingly unstoppable killing spree, sinking four vessels in the English Channel in under 96-hours, with the Allies seemingly unable to locate her. But was the Kriegsmarine’s stealthy U-boat really the potential war winner some later believed it could have been?

An Ordinary U-boat
Despite its later fame as the world’s first operational stealth submarine, U-480 began life as an ordinary Type VIIC U-boat. Laid down on 8 December 1942 and built by Deutsche Werke AG (werk no. 311) in Kiel, U-480 was commissioned less than ten months later. The Type VIIC was the workhorse of Germany’s underwater fleet, with almost 570 being built between 1941 and the end of the war. It proved an effective killer, operating in almost every area where the U-boat force was deployed.

Displacing 769 tons on the surface and 871 tons submerged, the Type VIIC was 220.25 feet long and was powered by two sets of diesel-electric engines, being capable of around 17.7 knots on the surface and 7.6 submerged. Its main armament included five torpedo tubes (four forward and one aft), typically carrying 14 torpedoes or 14 tube-launched mines. Secondary armament consisted of an 8.8 cm deck gun and several anti-aircraft guns of 3.7 cm and 2 cm calibre. Crewed by 44 to 52 men, the Type VIIC had a maximum theoretical range of 8,500 nautical miles if operating on the surface at 10 knots or 80 nautical miles at 4 knots submerged and could dive to a depth of 220 metres.

However, what made U-480 different to other Type VIIC U-boats was the fact it was covered with Anechoic tiles. Development of these synthetic rubber tiles – known commercially as Oppanol – had been given the codename ALBERICH by the Kriegsmarine, the name being drawn from the Old Norse collection of German legends called the Thidreksaga, in which Alberich, a dwarf, uses a cloak of invisibility.

Manufactured by the chemical giant I. G. Farben, the tiles measured roughly 1 m square and were 4 mm thick (they were in fact two 2 mm thick tiles stuck together) and had a series of small 2 mm wide holes. Within the material of the tiles were air cavities, which helped to degrade the reflection of ASDIC, the sonar system used by the Allies, thus reducing echoes by around 15% in the 10 to 18 kHz range, while the holes in the tiles further helped break up the sound waves. In addition, the tiles acted as a sound dampener, muffling the noise made by the U-boat’s engines. The Anechoic tiles were first tested on U-11 in 1940 and on U-67 in 1941 during sea trials, but it was not until 1944 that it was finally used operationally on U-480. The reason for the delay had been due to problems with the reliability of the adhesive used to stick the tiles to the hulls of the U-boats.

Hans-Joachim Förster
The commanding officer of U-480 throughout its service was Hans-Joachim Förster. Born in February 1920, Förster was a native of Groß Köris in Brandenburg, Germany, who began his service in the Kriegsmarine as an Offiziersanwärter in October 1938. A series of promotions followed, including: Fähnrich zur See (December 1939), Oberfähnrich zur See (August 1940), Leutnant zur See (April 1941) and finally Oberleutnant zur See (April 1943).

In 1941 and 1942, he was posted to the destroyer Z-29, a Type 1936A destroyer that took part in Unternehmen Zerberus (Operation CERBERUS), otherwise known as the Channel Dash, during which the battleships Scharnhorst, Gneisenau and the heavy cruiser Prinz Eugen, along with their escorts, attempted to run a British naval blockade of Brest and cut up through the English Channel in February 1942. In all, he took part in seven patrols with Z-29 until he was transferred to the U-boat force in July the same year.

Following his essential training in U-boats, Förster joined U-380 in the Mediterranean as watch officer for three patrols. However, after his promotion to Oberleutnant zur See, Förster was finally given his own command of U-348, a Type VIIC, in July 1943, although it was to be a short posting, for he was given command U-479, another Type VIIC, only a month later. He conducted no operational patrols while in command of either of these U-boats, and it was not until he took command of U-480 on 3 October 1943 that he finally got the chance to return to action.

First Patrol
On 11 June 1944, a Canadian Canso (the Canadian designation for the Consolidated PBY Catalina) flying boat of No. 162 Squadron RCAF, piloted by Flying Officer Lawrence Sherman, was operating out of RAF Wick in northern Scotland when it detected and attacked U-980 in the Norwegian Sea north of the Shetland Islands. The depth charges dropped by the Canso found their mark and sunk U-980, killing all 52 of her crew. Within 48 hours, Förster and U-480 would also encounter Sherman in a similar deadly contest.

Having departed Arendal in south-eastern Norway on 7 June, U-480 was heading for Brest in southern France when it was sighted by Sherman off the Norwegian coast in the early hours of the morning. Emboldened by their success several days earlier, the RCAF crew again attempted to attack their latest target with depth charges. However, as the Canso moved to attack U-480 it was hit by anti-aircraft fire coming from the U-boat, forcing it to perform a ditching in the open sea. Of the eight airmen aboard, seven, including Sherman, were killed or later died from exposure while struggling to survive clinging to a life raft. The only survivor was Flight Sergeant J. E. Roberts, who was taken prisoner of war. Having survived the attempted air attack, Förster and the crew of U-480 later arrived safely at Brest on 7 July.

Second Patrol
Förster’s second patrol began on 3 August, when he departed Brest bound for Trondheim in Norway. It would be during this patrol that U-480 would demonstrate the effectiveness of the Anechoic tile covering. On 21 August, the U-boat encountered HMCS Alberni, a Canadian Flower-class corvette, in the English Channel some 25 nautical miles south-east of St. Catherine’s Point on the Isle of Wight at around 11:45 hours. The Alberni was escorting a convoy and, despite having ASDIC installed, had been unable to detect U-480. Ordering his men into action, Förster fired several Zaunkönig torpedoes (known as German Navy Acoustic Torpedoes or GNATs by the Allies) at the corvette, hitting the vessel on her port side immediately behind the engine room. Sinking fast by her stern, the Alberni slipped beneath the waves in little more than 30 seconds, taking with her 59 out of her 90 crew.

The Alberni was the first Allied ship to be sunk with the assistance of ALBERICH, and she would not be the last. Indeed, Förster’s next kill came only a few hours later the next day. U-480’s second victim was HMS Loyalty, a British Royal Navy Algerine-class minesweeper. Having supported the Normandy landings the previous month, the Loyalty was en route back to Portsmouth in formation with several other minesweepers. However, one of the sweep-wires suddenly broke and so the Loyalty broke formation in order to recover the sweep. Watching this fateful move through his periscope was Förster, who again ordered his men into action. At 16:06 hours on 22 August, the minesweeper was suddenly struck by a GNAT torpedo fired from U-480 south-east of the Isle of Wight. Within less than seven minutes the Loyalty capsized, taking with her 18 (some accounts state 20) of her 48 crew. Again, the Anechoic tiles had proved their worth, the British vessels having been completely unaware of U-480’s presence.

It would be only a few hours before U-480 struck yet again in the English Channel. On 23 August the SS Fort Yale, a Canadian built Fort-class lend-lease cargo ship, was spotted at 17:58 hours about 17 miles south-east of St. Catherine´s Point. Having been damaged earlier while sailing in convoy, the Fort Yale entered the English Channel under tow of the British tug Hudson and the American tug Farallon. Förster’s crew prepared for action and again the order to fire his GNAT torpedoes was given. The semi-stricken cargo ship was hit and soon began to sink, although this time only one member of the crew was lost, 66 others being rescued and transported safely to Portsmouth.

The final success of U-480’s second patrol in the English Channel came several days later on the 25th. A straggler from convoy FTM-74, the British steam merchant ship Orminster, suddenly suffered a violent jolt and a loud explosion at 14:43 hours while about 35 miles north-west of Cap d’Antifer. Her crew knew almost immediately that she had been torpedoed and, realising she could not be saved, began to abandon ship. Her captain, 42 crew members, 13 gunners and an army storekeeper were picked up by HMS Pennywort and HMS Damsay, although two of the gunners later died from injuries sustained in the attack. Again, Allied ships in the English Channel had been unable to detect U-480.

A Knight’s Cross
Following the successful sinking of four Allied vessels, the U-480 arrived at Trondheim on 4 October, having spent a total of 63 days at sea. Förster had managed to sink an incredible 14,621 tons of Allied shipping, including two warships and two merchant vessels carrying vital supplies to Britain. The Oberleutnant zur See was convinced his success had been largely due to ALBERICH, which he believed had saved him from almost certain destruction.

Pleased with the results, and the fact earlier issues with the glue used to stick the tiles together were seemingly resolved, the Oberkommando der Marine (High Command of the Navy) considered ALBERICH a possible answer to the problem of ASDIC. However, there was still the not inconsiderable issue that it took several thousand man-hours to glue and rivet all the tiles to the hull of a U-boat, a major obstacle to fitting out large numbers of submarines. In addition, there was also a constant shortage of the synthetic rubber required to make the Anechoic tiles. The bottom line was, no matter how effective this new technology appeared to be, only a handful of additional U-boats could be coated with ALBERICH before the war ended. These included: U-485 U-486, U-1105 (the “Black Panther”), U-1106, U-1107, U-1304, U-1306, U-1308, U-4704, U-4708 (sunk prior to commissioning) and U-4709.

Nevertheless, Förster’s recent success was not going to go unrecognized. On 18 October 1944, two weeks after his return from his second patrol as commanding officer of U-480, he was awarded the coveted Knight’s Cross of the Iron Cross, having already received the German Cross in Gold the previous month. However, Förster’s luck was about to run out.

Brazier D2
On 6 January 1945, U-480 departed Trondheim on its third, and what would prove to be its final, patrol. Förster and his crew simply disappeared days later, never to be seen again. After the war, U-480 was thought to have been sunk by the British frigates HMS Duckworth and HMS Rowley in the English Channel between Land’s End and the Scilly Isles. However, in 1998 a wreck of a Type VIIC U-boat was discovered about 12 miles south-west of the Isle of Wight at the coordinates 50.22N, 01.44W, laying some 55 metres below the surface. A discovery that would eventually challenge the long-assumed belief of  U-480’s fate.

The following year, Dr. Innes J. McCartney, a British nautical archaeologist and historian, was able to identify the wreck as U-480. This finding led to further research to discover the true cause of the loss of the U-boat, and it was determined that Förster and his crew had likely fallen victim to a secret Allied underwater minefield codenamed Brazier D2. Although the exact date of the sinking of U-480 is not known, it is believed to have struck a mine sometime between 29 January and 20 February 1945. The blast having ripped off part of the stern section the vessel.

In his book, The Maritime Archaeology of a Modern Conflict, published in 2014, McCartney concluded: ‘The damage on U480 is not consistent with contact with a mine and remains unexplained. However, the intersection of the wreck with the Brazier D2 minefield means that the overwhelming evidence was that it was mined, with a partial detonation or acoustic trigger on the mine being the most likely explanation.’ All 48 men aboard died following the explosion, although one member of U-480’s crew, Rudergänger (Helmsman) Horst Rösner, had been lucky enough to be left behind in Norway to undergo training when she set sail on her fateful last voyage.

A Wunderwaffe?
In the years since the end of the Second World War, some have suggested that ALBERICH was a potential war winning Wunderwaffe (wonder weapon.) As with most such claims that have their origins in Nazi wartime propaganda, the truth is somewhat different and certainly less exciting. It is true that ALBERICH had proved quite effective in allowing U-480 and several other U-boats covered in the material to avoid detection. However, as already mentioned above, it took too long to apply to an entire U-boat and the necessary materials required were forever in short supply. In addition, the tiles were vulnerable to becoming detached or easily damaged; the resulting exposure of the hull, of course, would render the U-boat more detectable by ASDIC.

No Allied navies adopted the use of ALBERICH in the immediate post-war years, despite the advent of the Cold War and the increased threat from the Soviet Union. The British had learned of ALBERICH early in the war, although it’s unclear how much they understood its purpose at the time, and U-boats covered in the material fell into the hands of the Allies following the defeat of Germany. Yet, it was not until the 1970s that the Soviet Union began coating its submarines in rubber tiles, and both the Royal Navy and United States Navy only started using anechoic tiles on their submarines from 1980.

One example examined by the Allies post-war was U-1105, the so-called “Black Panther”, which was handed over by the British to the Americans for detailed research on her rubber outer skin by the Naval Research Laboratory and the Massachusetts Institute of Technology. From 1946 to 1949, U-1105 was subjected to varying types of tests including being sunk and raised again. However, in September 1949 she was blown up on the Potomac River near Piney Point. Here she lay in over 90 feet of water until her rediscovery in 1985 and subsequent designation as historic shipwreck preserve in 1994. Today, she remains the only physical reminder of project ALBERICH.