In the spring of 2003, the Norwegian minesweeperKNM Tyr , alerted by some fishermen, he discovered an unusual wreck near the island of Fedje, in the North Sea and 150 meters deep, which he had been searching for five years. It was the U-864, a German submarine from World War II that was the protagonist of a curious episode:it is the only documented case of a submarine sunk by another - the British HMS Venturer – while both were sailing underwater.
U-864 was an IXD2-class ship, a new series designed by the Kriegsmarine to outsize the previous IX. If this was conceived with the objective of carrying out operations far from its bases -in fact, it was used on the east coast of the USA, hindering the supply convoys that that country sent to Europe-, the IXD went a step further in length, weight and speed. 32 units were launched and another three remained half-built when the contract was canceled in September 1943.
The ship that the Norwegians found measured 87.58 meters and displaced 1,610 tons on the surface by 1,799 submerged. Propelled by two nine-cylinder diesel engines and another two six-cylinder ones for cruising, along with two more electric ones for surfacing, it could reach a speed of 20.8 knots (6.9 under water) and descend up to 200 meters deep. depth, with a range of 121 nautical miles (12,750 on the surface), depending on the speed applied. Likewise, she was armed with six tubes, 24 torpedoes, the standard SK C/32 cannon, the Flak M42, and two anti-aircraft machine guns. She entered service on August 12, 1943 under the command of the korvettenkapitän (Lieutenant Commander) Ralf-Reimar Wolfram, who would remain in command of him until the end.
Wolfram, born in Wilhelmshaven, Lower Saxony, in 1912, was a young officer who, leading U-108 (a slightly smaller IXB-class submarine), had sunk the SS Robert Gray in April. , a Liberty Ship (type of artillery freighter with which the USA made transports to Great Britain -and later to the USSR-). For what was to be his fourth mission, Wolfram was assigned to the new U-864 and assigned to the 4th Unterseebootsflottille , a training fleet commanded at the time by the fregattenkapitän (Frigate Captain) Heinz Fischer. He was later reassigned to the 33rd, which was under the command of the fregattenkapitän George Schewe, the man who with the U-105 had achieved no less than 16 sinkings in the same mission.
But the instructions given to Wolfram were very different. He did not have to send ships to the bottom but to transport military equipment to Japan, in what was baptized as Operation Caesar . Specifically, it had to carry 61 tons of mercury, stored in thirty steel bottles fixed to the keel. The Japanese had bought in Italy, before its surrender in September, 1,400 tons of that heavy metal that was used to make primers for explosives and that was scarce in their country. Also on board were V-2 projectile designs, jet aircraft parts, miscellaneous supplies, two engineers from the Messerschmitt company, and even a couple of Japanese military men, one an expert in torpedoes and the other in fuel.
The submarine sailed from Kiel on December 5, 1944 and entered the Norwegian naval base at Horten four days later to repair its snorkel (air intake). She then returned to the sea heading for Bergen, although she ran aground and, although she was able to free herself, she needed to make a stopover in Farsund to fix the damage. She arrived in Bergen on January 5, 1944 and there she suffered a new setback, being damaged by an aerial bombardment. Once repaired she resumed her voyage to Asia but by then the Allies had cracked the Enigma codes. , the machine the Germans used for their broadcasts, and learned what Wolfram's mission was. They immediately sent for him another submarine, the HMS Venturer.
The Venturer , a V-class submarine (of which 22 units were launched) was ostensibly smaller than U-864. It was 62.33 meters long, displaced 545 tons (740 submerged) and its Paxman engines also gave it a lower speed (11.25 knots on the surface and 10 underwater), apart from the fact that its armament was less forceful (four tubes , eight torpedoes, a deck gun and three anti-aircraft machine guns), although balanced with respect to its adversary for a confrontation between the two. In fact, one of the V-class's specialties was submarine hunting.
She entered service in May 1943 and for what was her eleventh mission she was commanded by Commander Jimmy Launders, an excellent mathematician who was considered a naval genius by his superiors and sailors, despite his youth; only 26 years old. In the last 12 months he accumulated 13 sunken enemy ships -including a submarine-, which outlined him as the ideal man to prevent the Operation Caesar . Showing off that ability, he set sail from Lerwock (Scotland) and as he approached Scandinavia he decided to turn off his ship's ASDIC, a sonar system without which it was more difficult to detect the enemy but which, in return, allowed him to go unnoticed. Using only the less sophisticated hydrophone, he seemed to reduce his chances of locating the German sub, but there was luck involved.
The U-864 had problems again:her engines emitted a rhythmic noise that if detected by the enemy could identify it, so Wolfram ordered, once again, to return to the port of Bergen. But he wouldn't give her time. The Venturer operator he caught that strange sound that he, at first, he attributed to a fishing boat, given how rare it would be on a German submarine. However, Launders's nose prompted him to take a look and peering through the periscope he could see the snorkel of the other outcropping nearby. He had discovered his target. At first he just followed it, waiting for it to surface to attack him, but Wolfram became aware of his presence and not only remained submerged but began to navigate in a zig-zag.
After three hours of pursuit and facing the risk that he would end up escaping, Launders decided to attack. In those conditions it was almost impossible to hit the target but let us remember his prodigious ability for mathematics; in a show, he calculated the movements that his opponent would make and the exact position that he would have at a certain moment. He then fired four torpedoes at as many different depths and at 17.5-second intervals. It seemed impossible for him to hit the target, with the aggravating circumstance that he was supposed to spend half the ammunition; in fact, three torpedoes missed. However, hearing the explosions, U-854 tried to evade with a diving maneuver that brought her directly into the room.
The torpedo exploded, splitting the hull in two and instantly sinking the submarine with its 73 crew members; none were saved. The misfortune of the Germans was especially bloody because they were only 31 nautical miles (57 kilometers) from Bergen. Launders, who had foiled Operation Caesar (although aided by the breakdowns and malfunctions of the German submarine, which caused him to lose a month), he was decorated with the Distinguished Service Order along with several members of his crew and entered history for being the only one to sink another submarine while being both submerged, something that had never happened (nor will it happen again). He would retire from the Royal Navy in 1974, passing away in 1988.
As an epilogue, it should be added that the Norwegian Navy was looking for the wreck after having found some documents that outlined what the dangerous cargo of the U-864 was. Dangerous because although it was not uranium oxide, as was feared a priori because it was what was being transported by another German submarine, the U-234 (merchandise also destined for Japan but which surrendered when its captain learned of Hitler's suicide), mercury is highly polluting and could poison fish and other marine animals. An analysis revealed that, in fact, the steel bottles where it was stored are corroded and lose about four kilos a year in total, which has forced fishing to be banned in the region.
The rescue is extremely difficult, since there are still four torpedoes left and the explosion of one of them could break part of the bottles, causing a mercury spill that would be an environmental catastrophe. So it was recommended to bury the wreck with a layer of sand and concrete with a thickness of 12 meters. After 15 years of deliberations, it was carried out in 2017 and today the U-864 rests under 160,000 tons of concrete, as if it were a gigantic tomb.
Fonts
The deadly trade. The complete history of submarine warfare from Archimedes to the present (Ian Ballantyne)/Code name Caesar. The secret hunt for U-Boat 864 during World War II (Jerome Preisler and Kenneth Sewell)/The mystery of U-33. Hitler's secret envoy (Nigel Graddon)/U-864-"Operation Caesar" (Deutsches U-Boot Museum)/Aboard his submarine, Jimmy Launders sank Ralf-Reimar Wolfram’s U-boat (Sebastien Roblin in War Is Boring)/Wikipedia