U-Boats in Foreign Service. German U-Boats were in demand both during WWII and long after the conflict was over! We all know the famed Class XXI U-Boat design inspired the Soviet Whiskey, US Tang, UK Porpoise, and Swedish Hajen classes of submarines after WWII, but even the modest Class VII and Class IX proved useful!
U-573 / G-7 / S-01
U-573 was launched in 1941 and went on three patrols. In 1942, during her third patrol, she was extensively damaged by a depth charge attack and managed to limp to Spain. The damage was too important and her crew could not patch the sub up. U-573 was therefore sold to Spain ! The ship was renamed G-7. However, the Spanish economy was in bad shape after the spanish Civil War and German spare parts or know-how were not readily available… Meaning G-7 was actually not repaired before 1947 ! By then G-7 was obsolete, yet, she was the most modern submarine in the Spanish navy. She was renamed S-01 in 1961 and was only retired in 1970 !
U-123 / Q165
U-123 had a rich history, taking part in the first Wolfpack as well as in Operation Drumbeat!
October 1940: Rise of the Wolfpack!
On the 5th of October 1940, a 35 ship convoy called SC-7 assembled off the coast of Canada and set off for the UK alongside 6 escorts. A straggler was sighted by U-124 on the 16th of October and was sunk. The next day, on the 17th of October 1940, U-38 sighted and sank another straggler while U-48 spotted SC-7. U-48 reported the sighting to the Kriegsmarine’s HQ which immediately vectored 5 submarines to intercept the convoy: U-46, U-99, U-100, U-101 and U-123. They formed one of the very first Wolfpack ever assembled. Meanwhile, U-48, which was trailing the convoy, managed to engage and sink 2 ships. The Wolfpack fell onto the convoy during the night of the 18th to the 19th of October. They sank 16 ships inside of 6 hours. The escorts were completely overwhelmed. When they chased one submarine away from the convoy, other subs would attack it. They often faced the choice between picking up survivors from the sea and falling behind the convoy or sticking to the convoy and leave the survivors to their grim fate, condemning them to a slow death…
While all the lookouts kept an eye on the perimeter of the convoy, some daring U-boat commanders actually attacked said convoy from within, surfacing in the middle of the ships and firing torpedoes at them undetected, almost at point blank range! The next day, the survivors of SC-7 braced for another attack: They were convinced the Wolfpack was trailing them and would attack at nightfall. By then, SC-7 had lost 20 ships out of 35 (79,592 Gross Registered Tons). What saved SC-7 that night was the apparition of another convoy in the vicinity: HX-79! The Wolfpack engaged their new prey, sinking 12 ships! This particular Wolfpack sank 32 ships in total, including 28 vessels inside of 48 hours. The members of the Wolfpack included U-boat aces such as Günther Prien, Joachim Schepke and Otto Kretschmer!
This action was the most successful U-boat attack of the whole war… It came as a shock to the Admiralty and forced the Royal Navy to adapt to the new reality of the Wolfpacks… It would take the Brits another 7 months to develop and deploy new tactics and weapons against the U-boats. This operation took place during a time German submariners called “The First Happy Time”: A period of total domination at sea that lasted from July 1940 to April 1941. 282 ally ships were sunk by German U-boats between July 1940 and October 1940 alone! From April 1941 onward, the tide of war turned against the U-boats… Until January 1942 and Operation Drumbeat, when seasoned U-boat commanders turned their attention against the green US Navy. This “Second Happy Time” was also called “American Shooting Season” and lasted until August 1942… 8 months during which the Germans sank 609 additional ally ships.
Beating the American drum: Korvettenkapitän Reinhard Hardegen and submarine U-123.
On the 11th of December 1941, four days after the Japanese attack on Pearl Harbour, Germany declared war on the USA. Soon after, Admiral Dönitz unleashed his U-boats on the unprepared Americans. Reinhard Hardegen skillfully and aggressively sailed U-123, sinking 18 ships over two Drumbeat patrols for a total of 106,000 Gross Registered Tons. Reinhard would often bottom his sub in shallow waters during the day, only surfacing at night to hunt for merchant shipping. Reinhard went on to be posted on shore duties after his second Drumbeat patrol, while U-123 sailed on under other captains. In summer 1944, considered old and unfit for duty, she was scuttled off the coast of Lorient, in France. The French would raise her in 1945, after the war, and refit her. She entered service in the French Navy under the name Blaison (Q165) and she remained in use until 1959.
U-766 / S610
Commissioned in July 1943, U-766 had a short but intense career with the Kriegsmarine, clocking in 5 whole patrols between February and August 1944! Decommissioned in the port of La Rochelle, she was still there in May 1945 when Germany surrendered. The French lost no time in pressing the submarine back into service for the Marine Nationale. U-766 was repaired and sea trials took place with a crew mostly composed of German prisoners of war. U-766 was commissioned as a French ship in 1946 under the name Laubie and pennant number S610.
Laubie had a hard time during her French service: They crashed her 3 times and sent her back to war in 1956 when she took part in Operation Musketeer (The Anglo-French operation to seize de Suez Canal). S610 was decomissioned in 1961.
U-511 / Ro-500
U-511 was a type IX-C long range U-boat. In 1942, the Germans decided to mount a rack of six Wurfkörper 42 rockets. (Basically, a bunch of 30cm Nebelwerfer rockets with a 45 kilos HE warhead and a range of 4.5 km) on her deck. And yes, she launched those rockets while submerged at a depth of 12 meters!
In the end, the Germans decided it was not worth the effort. The rockets lacked the accuracy to hit ships and the rack produced drag which impacted the performance and safe handling of the submarine when submerged. So using this system to target shore installations was not feasible. But the idea stuck. So the German scientists had a look into what else they could fire from a submarine… And they set their eyes on the V-1 cruise missile… Launching a cruise missile from a sub? Fancy that! However, because of the rivalry between services, the Luftwaffe refused to release some of its V-1s to the Kriegsmarine for testing. The Germans never got to try out this concept. The idea clearly stuck, though, because nowadays, most modern submarines have that capability. As for U-511, she was a very successful U-boat indeed. After several patrols, she travelled to Japan in 1943, where she entered service with the Japanese Imperial Navy under the name Ro-500.
U-570 / HMS Graph
HMS Graph: The Royal Navy’s very own Type VIIC U-boat!
HMS Graph started life as U-570 and was commissioned by the Kriegsmarine in 1941. She went on her first patrol with a green crew that only had two months of training (Germany was trying to rush as many subs into combat as possible by that time). On the 27th of August 1941, the sub spent most of the morning submerged to give its seasick crew some respite. But as soon as it tried to surface, it was attacked by a RAF Hudson ! The plane’s four depth charges fell very close to the sub as it was crash diving, causing it to almost roll over. Several leaks sprung up inside the U-boat and all the lights went out. In the engine room, panic ensued: The mechanics and electricians ran out of the compartment, fearing chlorine gas poisoning (Battery acid + Sea water). But by doing so, they basically condemned the ship to remain dead in the water and in the dark. Thinking the sub might sink, the crew blew the ballasts and surfaced. They spotted the British plane, still circling, and hoisted the white flag, not knowing the Hudson had actually dropped all of its Depth Charges already and was out of ammo !
What followed was a frantic exchange of messages, from both the sub and the plane, to their respective bases. The race was on… U-87 came close to reaching its colleagues, but ally air patrols prevented it from being able to do anything… A British Catalina took off from Reykjavík and was on the scene 3 hours later. The British warned the German sailors that they would be depth-charged should they try to scuttle their sub or try to dive and that no survivors would be picked up from the water. That threat was enough to scare the green crew and they cooperated. By 10pm, a British ship was on site and ordered the German crew to sleep inside their U-boat and prepare to be boarded the following day. The German crew, again, followed the order, but not before breaking their Enigma machine, cypher books, radios and torpedo firing computer and throwing the bits overboard. The following day, U-570 was boarded and towed back to Iceland. There, the sub was inspected and some damage control repairs were done to stop it taking on water. No signs of battery leakage or Chlorine gas emanations were found.
British and American officers and engineers then studied the ship thoroughly. One German G7a Torpedo was offloaded and sent to the USA. Shortly after, the captured ship sailed to the UK where she was placed in dry docks in Barrow. Once fully seaworthy, the British started testing the sub thoroughly and discovered that she dived much deeper than they first anticipated (230 meters instead of 170 meters). The first thing the British subsequently did was to modify their depth charges to take that new data into account. Both the Brits and Americans were very impressed by the design of the U-Boat. They loved the way she handled, they appreciated the fact the engines were mounted on rubber mountings to reduce the vibrations to her hull and therefore making her more silent/stealthier. The Americans wanted her Zeiss periscope to be outright copied for use on American ships, and the British particularly admired the German hydrophone array that was much better than the ones found on British subs. What both British and American disliked was the complete lack of comfort for the crew and the conditions in which they would have to operate the boats on long distance patrols… Nevertheless, the British decided to induct the captured German sub into the Royal Navy. The ship was renamed HMS Graph and subsequently went on three patrols, becoming the only U-boat to serve on both sides during WWII. The British also used her to make replicas of the main compartments, where British commandos and sailors could be trained on how to board similar ships, repair her and sail her. She served for over 2 years after which the British discovered another dark side of German U-boats: They were maintenance hungry: The engines needed servicing regularly and the batteries were only designed to operate at peak performance for a year… The lack of spare parts forced the Brits to decommission her from active service in February 1944. She was to be towed to the Clyde to be scrapped, but the tow line broke on the way and HMS Graph ran aground. She was partially salvaged and scrapped in 1947 and again in 1966.
U-2518 / S613
U-2518 was dommissioned in November 1944. By the time the U-boat had gone through her sea trials and her crew had been trained, the war was almost over: The ship was transferred for front line duty on the 1st of April 1945! Needless to say, she never saw action with the Kriegsmarine! She was surrendered to the British who sailed her to Northern Ireland before subsequently handing her over to the French as a War Prize. U-2518 arrived in Cherbourg in February 1946, was repaired and immediately sent for sea trials. In January 1948, U-2518 was transferred to the Mediterranean Fleet and sailed from Toulon to Casablanca completely submerged! The French loved the Type XXI! She was commissioned in the Marne Nationale as the Roland Morillot (S613). In 1956, S613 took part in Operation Musketeer. She went on to serve all the way to 1967.
This is by no means a definitive list of German U-Boats having served in navies other than the Kriegsmarine! There were many more. Type VII and IX mostly helped the Soviets and the allies bulk up their depleted fleets immediately after WWII although some of their features were also studied and replicated for domestic ship design. The Class XXI U-Boat however, is often considered the first real submarine: Designed for underwater use first and foremost, rather than simply being a submersible vessel that still had to spend most of its time on the surface. The Type XXI saw extensive service and sea trials at the hands of both allies and Soviets and ended up inspiring the Soviet Whiskey, US Tang, UK Porpoise, and Swedish Hajen classes of submarines, securing its legacy.