The U-Boats of World War Two

Under the terms of the Treaty of Versailles, Germany had been forbidden to retain or build any submarines. In actual fact the greater part of her fleet that was to take to the seas in 1939 was barely four years old. In the period 1919–34 German submarine development had continued. Her vessels had been built in foreign shipyards to German design, and co-ordinated and controlled by German technicians. Vessels were built in Turkey and in Finland, for example.

Gür was built in 1932 for the Turkish navy. She was 237 ft 6 in. long with a submerged displacement of 960 tons, and had six torpedo tubes and one 102 mm gun. Vesikko was built in Finland in 1933, and was essentially a coastal submarine, 133 ft 10 in. long with three torpedoes, a small gun and a submerged displacement of 300 tons. Vesikko was essentially the prototype of the Type II U-boat, and U-1 was launched in Kiel in June 1935. Further refinements were made until the Type IID was brought in in 1940, a larger vessel with a longer range. The Type I was based on Gür, as well as UB-49 from the First World War. These would become known as the Type VII, and they would become the mainstay of the German submarine fleet.

U-27, designed to be used in the Atlantic, was launched in 1936. U-30 was a Type VIIA, and she sank the liner Athena at the beginning of the war. The first Type VIIB was launched in April 1938; it had better engines and could carry more fuel. U-47, a Type VIIB, was commanded by Korvettenkapitän Günther Prien. He managed to penetrate Scapa low in 1939 and sink HMS Royal Oak. He was to go on to have a very successful war in the Atlantic.

The Type VIIC was brought in in 1940; it could carry more torpedoes, was more able to defend itself against aircraft attack and had a longer range. The German navy placed an order for 688 of them.

By the time Germany surrendered in 1945, 705 submarines of the Type VII had been brought into service. Of this total, 437 had been lost in action. Remarkably, U-977 in 1945 was based in Norway, and rather than surrender, it made a sixty-six-day submerged passage to Argentina, arriving there on 17 August 1945.

The crew were interned.

This was by no means the largest German type of U-boat. The Type IX had a far greater range. The first, U-37, came into service in August 1938. There were gradual refinements, giving these submarines an even greater range.

As the Germans had attempted to do in World War One, submarines were also used to carry cargo. The Type IXC had a cargo-carrying capacity of 252 tons, and was perfectly capable of travelling from Germany to the Far East. Type XB submarines were built as ocean-going minelayers with a range of 14,000 nautical miles. In order to increase the patrol endurance of their Type VII submarines, the Germans also developed a Type XIV, essentially a fuel tanker. It could carry 203 tons of fuel and four torpedoes that could be transferred to the Type VIIs.

Germany was desperately trying to create what she perceived to be a true submarine: in other words a vessel that did not have to spend a great deal of time on the surface, but could travel at a good speed under water. This became imperative as the Allies wrestled air superiority from the Germans in almost every theatre of war.

The key development was the Schnorkel, or snorkel. This allowed the submarine to be ventilated, enabling the submarine to use her diesel engines while she dived. In effect it was a long tube with a float-valve. The valve closed when it went below the water. Another development was the invention of the V-80 with a turbine engine. It broke down a high concentration of hydrogen peroxide to create oxygen and steam. Hydrogen peroxide, however, was very volatile. The Germans tested the V-80, which was a small submarine, and planned to apply it to the Type VII, but it never got further than the planning stage.

Other developments were the Type VIIA (1943). These too relied on the turbine engine, but also had standard diesel-electric drives. The Germans continued to experiment, desperately trying to create a submarine that could quickly dive and stay beneath the water for a considerable period of time and maintain a good underwater speed.

The Type XXI was a brand-new development of the design. It was streamlined and had high-capacity batteries. It would be capable of maintaining an underwater speed of 18 knots for ninety minutes; it would carry twenty-three torpedoes and have six bow tubes. It would also have impressive anti-aircraft and anti-ship armament. However, it would be useless for operations in the North Sea and English Channel because of its size.

Further variants were designed in 1944. The other major development was the XXIII, which used many of the developments of the XXI but was intended for coastal use. It would only have two torpedo tubes, and was considerably smaller, with a fraction of the displacement of the monster XXI. By August 1944 the Germans were giving priority to the construction of the XXI and the XXIII over the VII, but by this stage Allied bombing was making fabrication increasingly difficult. Between mid-February and mid-April 1945 no fewer than fourteen Type XXIs, which were virtually ready to become operational, were destroyed by Allied aircraft while still in Bremen, Hamburg and Kiel.

The first and only Type XXI to become operational was U-2511, and even then she was only launched on 18 March 1945. She left for her first operational patrol on 30 April out of Norway, but on 4 May, before she had even fired a single torpedo, she was ordered to surrender.

U-2321, the first Type XXIII, was launched from Hamburg in April 1944. Two further Type XXIIIs (U-2324 and U-2322) were launched between the end of January and the beginning of February 1945. In all, five Type XXIIIs carried out eight operational patrols.

On 17 August 1940 the Germans declared a total blockade of the British Isles. This was despite the fact that the German navy wanted a far more modest declaration to be made. It was in no way ready to enforce such a rigid total exclusion zone. But Germany was determined not only to sweep the British from the skies, but also to starve them as a prelude to invasion. The German navy would be expected to play its part in this.

As far as the German navy was concerned, the war had broken out five years too early; it was simply not ready. It had insufficient surface vessels and did not yet have a truly reliable and sufficiently large submarine force. The development of the submarine force had been the responsibility of Karl Dönitz. The primary target for the submarines was not enemy warships but their merchantmen. In order to beat Britain, her overseas trade needed to be interdicted, and food, munitions and vital supplies sent to the bottom of the ocean. Dönitz was of the opinion that a handful of submarines had no hope of achieving this, and he believed and wrote in a memorandum dated 1 September 1939 that he would need 300 submarines: 100 in the operational area, 100 en route or on their way back and 100 undergoing refitting and training in dock. As it was, he had fifty-seven, and only twenty-seven of them were capable of operating in the Atlantic.

Despite this, there was a very early success, as we have seen, when Prien penetrated Scapa Flow. This was not to be the last catastrophic loss at the hands of German submarines. Dönitz was firmly of the opinion that the Type VIIC (1942) was undoubtedly the best submarine in the world, but in reality it was relatively antiquated. Improvements were made by adding snorkels, anti-aircraft batteries, better torpedoes and shortwave transmitters. Germany desperately needed a new generation of submarines, but this was becoming increasingly difficult as systematically each and every German submarine shipyard was pulverised from the air. In the first two years of the war German submarine losses were relatively low, but this was not to be the experience of the majority of the submariners. In 1940, for example, the Germans were winning the loss-to-launch ratio: fifty-four were launched and twenty-six were lost. Dönitz needed, in order to keep up the pressure, forty new submarines a month. At best Germany was managing no more than twenty.

The most critical phase of the submarine programme was in 1942. The German navy wanted far more men and resources to be thrown into the U-boat campaign. During the year 238 submarines were brought into service, but eighty-eight were lost. By the peak of the battle of the Atlantic in 1943, German submarine wolf packs were inflicting grievous losses on the Allies. It appeared for a time that Germany was winning the war in the Atlantic. Then things began to change.

Convoys were zigzagging away from U-boat patrols as if they knew precisely where they were located. The submarines, when they picked up radio signals that had always led them to their prey, now found that the merchantmen were nowhere to be seen. The Germans could not discover the answer to the riddle, although every scrap of information was scrutinised. Had the wavelengths of the submarines been compromised? Or were enemy aircraft using unknown wavelengths? Before they could reach any conclusions, in May 1943 the Germans lost thirty-five submarines and managed to sink only 96,000 tons. Dönitz called off the Battle of the Atlantic, telling Hitler: ‘Our losses are too heavy. It is now essential that we conserve our strength, since otherwise we would merely play into the enemy’s hands.’

He went on to say, on 2 June: ’Under the present circumstances, it is pointless to send the U-boats out to fight. If there are enough shelters, it would be best to keep them there in safety until they can be equipped with new weapons.’

This was to mark a sea change in deference to the growing resources and power of the Allies. Henceforth, Dönitz believed that the submarines had to be used offensively still; otherwise they would be forced to fight a defensive war that they could never win. Hence the rationale behind the submarine warfare until the end of the war and the reason why thousands more German submariners would be doomed to die. The German submarines had not been betrayed except by themselves. The Allies were now picking up their radio signals and using radar that was effectively making the submarines helpless. They could now track the U-boats that were themselves shadowing convoys. But there was worse – the German codes had been cracked.

The Allies had outmanoeuvred the German submarine force, but it continued to fight on. There was no other real option for the Germans, though the last time German surface vessels ventured into the Bay of Biscay was December 1943. They found themselves hounded by the Royal Navy. The surface vessels were now reduced to coastal operations, yet the U-boats still roamed the Atlantic. Having failed to prevent men, munitions and supplies from reaching Britain, and unable to penetrate to any great extent the intricate network of Allied vessels, aircraft and minefields protecting the Allied entry point into mainland Europe, the submarines could not hope to make a major strategic impact on the course of the war.

By the time Germany finally accepted unconditional surrender in May 1945, only 150 submarines were left, little more than 15% of her vast, 1,000-strong submarine fleet. They hoisted black flags, and the Royal Navy led them to their destruction. Operation Deadlight saw them scuttled en masse.

U-boat types

German submarines were developed clandestinely, inasmuch as the Versailles Treaty prohibited them in the German Navy. Design work, both at IvS and by the Blohm und Voss firm, continued for foreign navies with production undertaken in the customer’s yards under German supervision. These boats also served as prototypes for domestic production, which made it possible for the first new German submarine, the U-1, to be completed on 29 June 1935, only five weeks after the repudiation of the Versailles Treaty.

The overwhelming majority of the 1,150 U-boats commissioned between 1935 and 1945 belonged to two groups: the so-called 500- ton Type VII medium boats, and the 740-ton Type IX long-range submarines. The Type VIIC actually displaced between 760 and 1,000 tons on the surface, had a cruising range of 6,500 to 10,000 miles at 12 knots on the surface and 80 miles at 4 knots submerged. They had a battery of 5 torpedo tubes with 14 torpedoes, an 88mm deck gun, and ever-increasing numbers of light antiaircraft weapons. Almost 700 of these boats in all of their variants entered service during World War II. The Type XIC actually displaced 1,120 tons; it had a cruising range of 11,000 miles at 12 knots on the surface and 63 miles at 4 knots submerged. They had a battery of 6 torpedo tubes with 22 torpedoes, a 105mm deck gun, and ever-increasing numbers of light antiaircraft weapons. Almost 200 of this type and its variants were commissioned.

Germany also commissioned a number of other important types during World War II. Among the most important were the Type X minelayers and the Type XIV supply boats. Both types operated as resuppliers for the operational boats during the Battle of the A tlantic, providing fuel, provisions, medical supplies, reload torpedoes, and even medical care and replacement crew members. Consequently they became prime targets for Allied antisubmarine forces, and few survived. The other major vessels were the radical Type XXI and Type XXIII boats, designed for high submerged speed and extended underwater operation. Revolutionary streamlined hull shapes, greatly increased battery space, and the installation of snorkels allowed these boats to operate at submerged speeds that made them very difficult targets for Allied antisubmarine forces. Confused production priorities, however, and the general shortage of materials late in the war prevented more than a very few from putting to sea operationally.

TYPE IIA (1921)

The prototype for this class was designed by the IvS for Finland and was based on the UBII type from World War I. The same design was used for new coastal submarines when Germany recommenced U-boat construction. The German boats operated primarily in training and trials roles, although they undertook operational patrols during the first eight months of World War II. The U-1 was mined off Terschelling on 8 April 1940; a training accident sank the U-5 outside Pillau on 19 March 1943; the fishing vessel Helmi Söhle accidentally rammed and sank the U-2 near Pillau on 8 April 1944. The other three boats decommissioned on 1 August 1944.

TYPE IIB (1935)

These submarines were modestly lengthened versions of the previous Type IIA boats. They served mainly as training vessels except in the early months of World War II, when they undertook operational patrols. The U-12 was mined in the English Channel on 5 October 1939, and the trawler Cayton Wyke and patrol vessel Puffin sank the U-16 there on 25 October. The torpedo boat Iltis accidentally rammed and sank the U-15 off Heligoland Bight on 30 January 1940; the U-22 was mined in the North Sea on 23 March; the sloop Weston sank the U-13 near Newcastle-upon-Tyne on 31 May. A training accident sank the U-7 in the Baltic on 18 February 1944; the U-19 and the U-20 were scuttled off the Turkish coast in the Black Sea on 10 September; Soviet aircraft sank the U-9 there on 20 September. The surviving boats were scuttled in port in May 1945.

TYPE VIIA (1936)

These boats used an improved version of the IvS design for the Finnish Vetehinen, and were the precursors of the Kriegsmarine’s most important type of Atlantic submarine during World War II. They conducted operational patrols until the end of 1940, when surviving boats became training vessels. The destroyers Forester and Fortune sank the U-27 off the Scottish coast on 20 September 1939; the destroyers Icarus, Kashmir, and Kingston sank the U-35 off the Norwegian coast on 29 November; the submarine Salmon torpedoed the U-36 near Kristiansand on 4 December. The minesweeper Gleaner sank the U-33 in the Firth of Clyde on 12 February 1940; a British aircraft sank the U-31 in the Jade on 11 March; the destroyers Harvester and Highlander sank the U-32 off the Irish coast on 30 October. The submarine tender Lech accidentally rammed and sank the U-34 at Memel on 5 August 1943, and an accident sank the U-28 at Neustadt on 17 March 1944. The two surviving boats were scuttled on 4 May 1945 at Flensburg.

TYPE VIIB (1938)

These were slightly enlarged versions of the Type VIIA with greater range and space for more reload torpedoes. They undertook operational patrols until late 1943, when the surviving boats became training vessels. The U-48 was the most successful U-boat of World War II, sinking 306,875 tons of shipping. The destroyers Inglefield, Intrepid, and Ivanhoe sank the U-45 off the Irish coast on 14 October 1939. British and French antisubmarine vessels sank the U-55 near the Scilly Isles on 30 January 1940; the U-54 was mined in the North Sea on 14 February; the destroyer Gurkha sank the U-53 in the Orkney Islands on 23 February; the U-50 was mined off Terschelling on 7 April; the destroyers Brazen and Fearless sank the U-49 near Narvik on 15 April; the destroyer Vansittartsank the U-102 in the Bay of Biscay on 1 July. The U-47 was lost near Rockall on 7 March 1941; the destroyers Vanoc and Walker sank the U-99 and the U-100 south of Iceland on 17 March; the sloop Scarborough and destroyer Wolverine sank the U-76 in the same area on 5 April. The destroyer Roper sank the U-85 off Cape Hatteras on 14 April 1942; the destroyers Wishart and Wrestler sank the U-74 east of Cartagena on 2 May, and the destroyer Kipling sank the U-75 near Mersa Matruh on 28 December. A British aircraft sank the U-83 near Cartagena on 4 March 1943, and the Canadian destroyer St. Croix and corvette Shediac sank the U-87 the same day off Leixoes. A U. S. aircraft sank the U-84 in the western Atlantic on 7 August; the U-86 failed to return from an Atlantic patrol in November; the destroyers Trippe and Woolsey sank the U-73 near Oran on 16 December. The four surviving boats were scuttled in May 1945.

TYPE IX (1938)

The design for these long-range oceanic boats was developed from the Type IA to incorporate greater range and a heavier gun armament. The first two became training boats in December 1941. The destroyers Faulknor, Firedrake, and Foxhound sank the U-3 9 northwest of Ireland on 14 September 1939; the U-40 was mined in the English Channel on 13 October; the destroyers Ilex and Imogen sank the U-42 southwest of Ireland on the same day. The destroyer Antelope sank the U-41 south of Ireland on 5 February 1940, and the U-44 was mined off Terschelling on 13 March. Aircraft from the escort carrier Santee sank the U-43 near the Azores on 30 July 1943. The two surviving boats were scuttled in May 1945.

TYPE IIC (1938)

This type was a developed version of the previous Type IIB. They became training vessels from the end of 1940. The destroyers Escort, Imogen, and Inglefield and the submarine Narwhal sank the U-63 off the Shetland Islands on 25 February 1940, and the rest of the class were scuttled in May 1945.

TYPE IXB (1939)

This class had slightly greater range than the previous Type IX. An aircraft from the battleship Warspite sank the U-64 off Narvik on 13 April 1940; the U-122 failed to return from a patrol in June, as did the U-104 in November. The destroyer Douglas sank the U-64 southeast of Iceland on 28 April 1941; the destroyers Broadway and Bulldog and the corvette Aubretia captured the U-110 south of Iceland on 9 May and sank it the next day, and the trawler Lady Shirley sank the U-111 southwest of Tenerife on 4 October. The sloop Black Swan and the corvette Stonecrop sank the U-124 off Oporto on 2 April 1943; a British aircraft sank the U-109 south of Ireland on 4 May; a French aircraft sank the U-105 off Dakar on 2 June, and Australian and British aircraft sank the U-106 in the Bay of Biscay on 2 August. The U-108 was bombed at Stettin on 11 April 1944, and British aircraft sank the U-107 in the Bay of Biscay on 18 August. The U-103 was bombed at Kiel on 15 April 1945. The U-123 was scuttled at Lorient on 19 August 1944. It was raised, became the French Blaison, and was decommissioned on 18 August 1959.

TYPE IID (1940)

These final conventional coastal boats operated mainly as training submarines. The corvette Periwinkle and the destroyer Wanderer sank the U-147 northwest of Ireland on 2 June 1941; the destroyers Faulknor, Fearless, Foresight, Forester, and Foxhound sank the U-138 off Cadiz on 18 June, and the Russian submarine Schc-307 torpedoed the U-144 in the Gulf of Finland on 10 August. The surviving boats were scuttled or surrendered at the end of World War II

TYPE VIIC (1940), U-251 (1941)

The Type VIIC was the backbone of the German submarine force during operations in the Atlantic and Mediterranean from 1940 onward. It was a further improvement on the basic Type VII design. Many received much heavier antiaircraft batteries, usually twin or quadruple 20mm mounts, after Dönitz made the decision to have U-boats fight their way past aircraft on the surface. They also received radar warning receivers and other electronic upgrades as the war continued.

This class suffered appalling casualties. Twenty-one boats were lost in 1941, two (the U-580 and the U-583) in accidents and one (the U-570) captured by the British and commissioned into the Royal Navy as the Graph. Sixty-one became casualties during 1942 and one, the U-573, was interned in Spain and became the Spanish G-7, remaining in ser vice until 1970. During 1943 another 114 boats were lost, seven of them (the U-284, the U-649, the U-659, the U-670, the U-718, the U-768, and the U-983) in accidents. Casualties in 1944 were even higher, with 153 boats lost, only three (the U-673, the U-737, and the U-738) as a result of accidents. Finally, 57 boats were lost in 1945, two (the U-1053 and the U-1206) in accidents. More than half the 106 boats that survived until May 1945 were scuttled by their crews to prevent their seizure by Allied forces. Virtually all the others were destroyed by the Allies, although one, the U-977, fled to Argentina, where it was interned before being handed over to U. S. forces. In total, Allied antisubmarine forces sank no fewer than 370 of the 492 boats of this class that commissioned during World War II.

TYPE IXC (1940)

These boats were slightly larger than the previous Type IXB group and had enhanced range and antiaircraft batteries. The Canadian corvettes Chambly and Moosejaw sank the U-501 in the Denmark Straits on 10 September 1941; the Australian destroyer Nestor sank the U-127 near Gibraltar on 15 December; antisubmarine vessels and aircraft sank the U-131 off Madeira on 17 December. Aircraft sank the U-503 and the U-520 off Newfoundland on 15 March and 30 October 1942, the U-158 near Bermuda on 30 June, the U-502 and the U-165 in the Bay of Biscay on 5 July and 27 September, the U-512 off Cayenne on 2 October, and the U-517 southwest of Ireland on 21 November. The cutter Thetis sank the U-157 off Havana on 13 June, the PC-566 sank the U-166 in the Gulf of Mexico on 1 August; the U-171 was mined near Lorient on 8 October; the destroyers Quick, Swanson, and Woolsey sank the U-173 near Casablanca on 16 November. Almost half the class were lost during 1943. The U-519 failed to return from an Atlantic patrol in January. Aircraft sank the U-164 off Pernambuco on 6 January, the U-507 northwest of Natal on 13 January, the U-156 east of Barbados on 8 March, the U-524 near Madeira on 22 March, the U-174 off Newfoundland on 27 April, the U-514 in the Bay of Biscay on 8 July, the U-506 west of Vigo on 12 July, the U-513 off the Brazilian coast on 19 July, the U-159 east of Jamaica on 28 July, the U-161 near Bahia on 27 September, and the U-508 in the Bay of Biscay on 12 November. Escort carrier aircraft sank the U-160 south of the Azores, the U-509 near Madeira, and the U-67 in the Sargasso Sea between 14 July and 16. The sloop Totland sank the U- 522 off Madeira on 22 February; the destroyer Champlin sank the U-130 near the Azores on 12 March; the Canadian corvette Prescott sank the U-163 northwest of Cape Finisterre the next day; the cutter Spencer sank the U-175 off Ireland on 17 April; the destroyer Oribi and the corvette Snowflake sank the U-125 east of Newfoundland on 6 May; the Cuban patrol boat CS-13 sank the U-176 near Havana on 15 May; the destroyers Jouett and Moffett and aircraft sank the U-128 near Pernambuco on 17 May; the PC-565 sank the U-521 off the Maryland coast on 2 June; the sloops Kite, Wild Goose, Woodpecker, and Wren sank the U-504 northwest of Cape Ortegal on 30 July; the corvette Wallflower and the destroyer Wanderer sank the U-523 west of Vigo on 25 August; the destroyers Pathfinder, Quentin, and Vim y sank the U-162 near Trinidad on 3 September; the Bogue group sank the U-172 off the Canary Islands on 13 December. U.S. hunter-killer groups sank the U- 515 and the U-68 near Madeira on 9 and 10 April 1944 and the U-66 near the Cape Verde Islands on 6 May, and they captured the U-505 west of Africa on 4 June. Aircraft sank the U-126 in the Bay of Biscay on 3 July, and the destroyer escorts Frost and Inch sank the U-154 west of Madeira the same day. The U-129 was scuttled at Lorient on 18 August. The destroyer escorts Carter and Neal A. Scott sank the U-518 west of the Azores on 22 April 1945. The U-511 was transferred to Japan on 16 September 1943 as the RO-500, was surrendered, and scuttled postwar. The U-155 and the U-516 surrendered and were scuttled postwar. The U-510 surrendered on 12 May 1945, became the French Bouan, and was stricken on 1 May 1959.

TYPE XB (1941)

These very large minelayers (Germany ‘s largest wartime boats) carried their mines in vertical tubes, twelve on each side (each containing two mines) built into the main ballast tanks and six (each containing three mines) in a large forward hull compartment. They were used extensively as supply submarines to support Atlantic operations and for blockade running. The U-116 failed to return from an Atlantic patrol in October 1942. Escort carrier aircraft sank the U-118, the U-117, and the U-220 in the Atlantic on 12 June, 7 August, and 28 October 1943 respectively. The sloop Starling sank the U-119 in the Bay of Biscay on 24 June 1943, and the destroyer escorts Baker and Thomas sank the U-233 southeast of Halifax on 5 July 1944. The U-219 became the Japanese I-505 in May 1945 and was surrendered in August at Djakarta. The U-234 surrendered in May 1945 and was scuttled.

TYPE XIV (1941)

These boats were designed as specialized supply submarines to support Atlantic operations and were known popularly as milchkuh (milk cow). Allied antisubmarine forces made a successful concerted effort to destroy these boats. Aircraft sank the U-464 and the U-489 southeast of Iceland on 20 August 1942 and 5 August 1943, and the U-463, the U-459, and the U-461 in the Bay of Biscay on 16 May, 24 July, and 30 July 1943. Escort carrier aircraft sank the U-460, the U-487, and the U-490 in the Atlantic on 16 April and 13 July 1943 and 12 June 1944. The sloops Kite, Wild Goose, Woodcock, and Woodpecker sank the U-462 in the Bay of Biscay on 30 July 1943, and the destroyer escorts Barber, Frost, Huse, and Snowden sank the U – 488 west of the Cape Verde Islands on 26 April 1944.

TYPE VIID (1941)

These minelayers were based on the Type VIIC design with an additional compartment inserted abaft the conning tower to accommodate five vertical mine tubes. The trawler Le Tiger sank the U-215 east of Boston on 3 July 1942; the sloops Erne, Rochester, and Sandwich sank the U-213 east of the Azores on 31 July, and aircraft sank the U-216 southwest of Ireland on 20 October. Aircraft from the escort carrier Bogue sank the U-217 in the central Atlantic on 5 June 1943, and the frigate Cooke sank the U-214 in the English Channel on 26 July 1944. The U-218 surrendered in May 1945 and was scuttled.

TYPE IXD-2 (1941)

These boats used a conventional power plant to achieve a slightly higher surfaced speed than the earlier Type IXC. The U-883 was the only example commissioned of the Type IXD/42, which had a greatly increased range of 31,000 nautical miles. Twenty-three additional Type IXD/42 boats were canceled. Aircraft sank the U-200 southwest of Iceland on 24 June 1943, the U-199 east of Rio de Janeiro on 31 July, the U-197 near Madagascar on 20 August, the U-849 west of the Congo river on 25 November, the U-848 and the U-177 off Acension Island on 5 November 1943 and 6 February 1944, the U-871 northwest of the Azores on 26 September and the U-863 near Recife three days later, and drove the U-852 ashore on the Somali coast on 3 May. Escort carrier aircraft sank the U-847 in the Sargasso Sea on 27 August 1943, the U-850 west of Madeira on 20 December, and the U-860 off St. Helena on 15 June 1944. The destroyer Active sank the U-179 near Capetown on 8 October 1942; the destroyer Mackenzie sank the U-182 near Madeira on 16 May 1943; the frigate Findhorn and the Indian sloop Godavari sank the U-198 near the Seychelles on 12 August 1944; the submarine Trenchant torpedoed the U-859 in the Malacca Straits on 23 September; the submarine Venturer torpedoed the U-864 while both were submerged off Bergen on 9 February 1945. The U-851 and the U-196 failed to return from patrols to the Indian Ocean in April and November 1944. The U-872 was stricken after USAAF bombers badly damaged it at Bremen on 29 July 1944, and the U-178 was scuttled at Bordeaux on 25 August. The U-181 and the U-862 became the Japanese I-501 and I-502 in May 1945 and were surrendered at Singapore in August. The surviving boats were surrendered at war’s end.

TYPE IXD-1 (1941)

These boats were designed as faster versions of the Type IXC and used six S-boat engines. They were converted to transport submarines to carry 250 tons of freight in 1943 with two replacement Germania diesel engines generating 1400 bhp (top speed: 15.75 knots) and all torpedo tubes removed. The U-180 was lost in the Bay of Biscay in August 1944. The U-195 became the Japanese I-506 in May 1945 and was surrendered in August at Djarkarta.

TYPE IXC/40 (1942)

These boats were similar to the earlier Type IXC, with heavier antiaircraft batteries and slightly greater range. A n additional 59 units were either destroyed on the slip or canceled. The U-183 failed to return from an Atlantic patrol in November 1942, as did the U-529 in February 1943, the U-193 in April 1944, the U-866 and the U-865 in September 1944, the U-1226 in October 1944, and the U-857 in April 1945, The U-526 was mined off Lorient on 14 April 1943, as were the U-854 and the U-803 in the Baltic on 4 February and 27 April 1944. Aircraft sank the U-169, the U-194, and the U-844 south of Iceland on 27 March, 14 June, and 16 October 1943, the U-167 near the Canary Islands on 6 April, the U-189 and the U-540 off Greenland on 23 April and 17 October, the U-585 in the Bay of Biscay on 5 July, the U-5 3 3 in the Gulf of Oman on 16 October, and the U-542 off Madeira on 28 November. Escort carrier aircraft sank the U-527, the U-628, and the U-185 west of the Azores on 23 July, 11 August, and 24 August. The destroyers Beverley and Vimy sank the U-187 in the North Atlantic on 4 February; the destroyer Hesperus sank the U-191 off Greenland and the U-186 west of the Azores on 23 April and 12 May; the corvette Loosestrife sank the U-192 off Greenland on 6 May; the destroyer Vidette sank the U-531 off Newfoundland the same day; the sloop Fleetwood and aircraft sank the U-528 southwest of Ireland on 11 May; the frigate Byard sank the U-841 off Greenland on 17 October; the sloops Starling and Wild Goose sank the U-842 in the western North Atlantic on 6 November; the frigate Nene and the Canadian corvettes Calgary and Snowberry sank the U-536 off the Azores on 20 November; the sloop Crane and the frigate Foley sank the U-538 southwest of Ireland the next day. Aircraft sank the U-545 off the Hebrides on 10 February 1944, the U-846 and the U-1222 in the Bay of Biscay on 4 May and 11 July, and the U-1225 and the U-867 off Bergen on 24 June and 19 September. Escort carrier aircraft sank the U-544, the U-543, and the U-1229 in the central Atlantic on 16 January, 2 July, and 20 August, and the Block Island group sank the U-801 there on 17 March. British and Canadian antisubmarine vessels sank the U-845 in the North Atlantic on 10 March; the destroyer Champlin and the destroyer escort Huse sank the U-856; the destroyer escorts Gandy, Joyce, and Peterson sank the U-550 off New York on 7 and 16 April ; the destroyer escorts Ahrens and Eugene E. Elmore sank the U-559 off Madeira on 29 May; the Dutch submarine Zwaardvisch and the U. S. submarine Flounder sank the U-168 and the U-537 in the Java Sea on 6 October and 9 November; the Canadian corvette S t. Thomas sank the U-877 northwest of the Azores on 27 December. Aircraft sank the U-843 and the U-534 in the Kattegat on 9 April and 5 May 1945. USAAF aircraft bombed the U-870 and the U-1221 in Bremen and Kiel on 30 March and 3 April. Hunter killer groups in the North Atlantic sank the U-866 on 18 March, the U-1235 on 15 April, the U-880 on 16 April, the U-546 and the U-548 on 24 April, and the U-879 on 30 April. The destroyer escorts Howard D. Crow and Koiner sank the U-869 off New Jersey on 11 February; the corvette Tintagel Castle and the destroyer Vanquisher sank the U-878 in the Bay of Biscay on 10 April; the submarine Besugo torpedoed the U-183 in the Java Sea on 23 April; the destroyer escort Farquhar sank the U-881 off Newfound land on 6 May; and the destroyer escort Atherton and the frigate Moberly sank the U-853 off New London the same day. The U-1224 became the Japanese RO-501 in February 1944 and was sunk by the destroyer escort Francis M. Robinson off the Cape Verde Islands on 13 May 1944. The surviving boats were surrendered or scuttled in May 1945, apart from the U-1231 , which became the Soviet B-26 in 1947 and was stricken in 1960.

TYPE VIIC 41 (1943)

This final production development of the basic Type VII design featured a stronger hull that permitted an increase in the diving depth to over 500 feet. Many boats also commissioned with heavier antiaircraft batteries, usually a single 37mm gun and four 20mm weapons. This group also suffered heavy casualties. Nine boats were sunk during 1944, two (the U-1013 and the U-1015) in accidents, and a further 23 in 1945. Sixteen boats were scuttled to prevent their seizure by Allied forces at the end of the war, and 31 boats were surrendered. One, the U-995, became a museum vessel postwar.

TYPE VIIF (1943)

These boats were lengthened versions of the Type VIIC. They were designed to supply torpedoes to Atlantic boats and carried 24 torpedoes in the additional compartment, 10 in the torpedo rooms (five in the tubes and five reloads) and five more in pressure-tight compartments on top of the pressure hull. Aircraft from the escort carrier Block Island sank the U-1059 southwest of the Cape Verde Islands on 19 March 1944; the destroyer escort Fessenden sank the U-1062 in the central Atlantic on 30 September; aircraft from the carrier Implacable drove the U-1060 ashore at Bronnoysund on 27 October. The U-1061 was surrendered in May 1945.

TYPE XXIII (1944), U-2326 (1944)

The Type XXIII boats were the coastal equivalents of the new Type XXI oceanic submarines. Like them, they brought together a hull designed for high underwater speed with more powerful batteries, powerful electric motors, and snorkels to maximize their operations while submerged. In addition to their main motors, these boats also used a low-power motor for silent, slow-speed operation. Their small size, however, was a major disadvantage, since they were very crowded internally and had no space for reload torpedoes, which limited their suitability for operations. A total of 491 units of this type were ordered, of which 61 were completed and commissioned, but only 6 undertook operations. The U-2323 and the U-2341 were mined in the Baltic on 26 July and 26 December 1944. British aircraft sank the U-2338 north of Frederika on 4 May 1945. The U-2331, the U-2344, and the U-2367 were lost in accidents. Almost all of the other boats were either scuttled or surrendered in May 1945. The U-2353 became the Soviet N-31 in 1948 and was scrapped in 1963, and the U- 4706 became the Norwegian Knerter in 1948 and was stricken in 1954. The Federal German Navy salved the U-2365 and the U-2367 in 1956, reconstructed them with 600-horsepower diesel-electric machinery and new superstructures, and commissioned them as the Hai and the Hecht. They were scrapped in 1968-1969.

TYPE XXI (1944)

The Type XXI boats were the most influential submarine type of World War II on postwar submarine development. The design brought together a hull optimized for high underwater speed with more powerful batteries, powerful electric motors, and snorkels to maximize their operations while submerged. In addition to their main motors, these boats also used low-power motors for silent, slow-speed operation. They had good torpedo batteries, antiaircraft mounts faired into the sail, and advanced radar and sensor suites that retracted into the sail for streamlining. Orders were placed for 739 boats, but only 118 were completed and commissioned; the U-2511 alone undertook an operational mission. The U-3520 and the U-3519 were mined in the Baltic on 31 January and 2 March 1945. British aircraft sank or wrecked the U-2503, the U-2521, the U- 2524, and the U-3032 in Flensburg Fjord on 3 May, and another sank the U-3523 in the Skagerrak on 6 May. Allied bombing raids sank 12 of the type in port during 1945 before they became operational for front-line duties. Almost all the other boats were scuttled or surrendered in May 1945. The U-3008 went to the United States for trials and experiments and was sunk as a target in May 1954. The U-2529, the U-3035, the U-3041, and the U-3515 became the Soviet B-27 through the B-30 and were broken up in 1958. Components of at least 11 other boats were seized by the Soviets, but it is not certain that they were completed and put into service. The U-2540 was salved by the Federal German Navy in 1957, reconstructed with new 1200-horsepower dieselelectric machinery and revised superstructure, and commissioned in 1960 as the Wilhelm Bauer. It was decommissioned on 15 March 1983 and transferred to the Deutsches Schiffahrtsmuseum in Bremerhaven as an exhibit.

 

U-BOAT OPERATIONS IN WORLD WAR II

The outbreak of World War II found the German submarine arm well trained but deficient in numbers. From the moment of its reestablishment, the submarine force had concentrated much of its effort on validating Kommodore Karl Dönitz’s concepts for an all-out assault on enemy trade using concentrated groups of submarines under central shore-based control to locate and destroy convoyed shipping, primarily through surfaced night attacks (wolf-pack tactics). Dönitz was promoted Konteradmiral in October 1939, but shortages of U-boats, Adolf Hitler’s initial insistence on Germany’s adherence to the Prize Regulations, and demands on the submarine force for its support of surface naval operations prevented him from exploiting the potential of the wolf-pack tactics for most of the first nine months of the conflict. On average only six boats were at sea at any one time during this period, forcing them to attack individually, although some attempts were made to mount combined attacks whenever possible.

As a result of its World War I experience after 1917, Britain was quick to begin the convoying of merchant vessels. There was some initial hesitation because of the feared detrimental effect that convoys could have on the efficient employment of shipping, but when the liner Athena was torpedoed and sunk without warning on 3 September 1939, Britain took this to indicate that Germany had commenced an unrestricted campaign of submarine warfare against merchant vessels. Regular east coast convoys between the Firth of Forth and the River Thames started on 6 September and outbound transatlantic convoys from Liverpool two days later.

The conquest of Norway and the collapse of France in June 1940 brought substantial changes to the U-boat war against trade. From French bases, German reconnaissance and long-range bomber aircraft operated far into the Atlantic, while the operational range of the U-boats sailing from Norway and French Biscay ports increased dramatically. Italy’s simultaneous entry into the war terminated all commercial traffic in the Mediterranean except for very heavily escorted operational convoys bringing supplies into Malta. It also substantially increased the number of submarines available for the Atlantic campaign against shipping, inasmuch as Italian submarines began operating from Biscay ports, effectively doubling the total Axis force at sea. This situation allowed Dönitz to introduce his wolf-pack tactic on a large scale into the Atlantic shipping campaign, just as the British faced an alarming shortage of oceanic convoy escorts because of the neutralization of the French Fleet and their decision to retain destroyers in home waters to guard against a German invasion. The results vindicated Dönitz’s belief in the effectiveness of wolf packs. In the first nine months of the war, German U-boats sank a little more than 1 million tons of shipping, whereas they and the Italians together destroyed more than 2.3 million tons between June 1940 and February 1941. However, the release of destroyers from their guard duties, the addition of new escorts, and the transfer of fifty obsolete destroyers from the U. S. Navy improved the situation. The dispersal point for westbound transatlantic convoys and the pickup point for escort groups meeting eastbound shipping gradually moved westward as the range of the escorts was increased. This pushed the main arena of Axis submarine operations more toward the mid-Atlantic zone, which reduced the time that boats could spend on station. In mid-1941 the United States imposed its so-called Neutrality Zone on the western Atlantic and began escorting British convoys in conjunction with Royal Canadian Navy escorts, operating from Argentia in Newfoundland. North Atlantic convoys now were escorted throughout by antisubmarine vessels. Nevertheless, these additions to the escort force had only a limited impact on losses, since German and Italian submarines succeeded in sinking a further 1.8 million tons in the following nine months prior to the U. S. entry into the war.

The German declaration of war on the United States on 10 December 1941 brought a major westward expansion of U-boat operations against shipping. A disastrous period followed, while the U. S. Navy struggled with the problems of finding the escorts and crews required to convoy the enormous volume of merchant traffic along the East Coast of the United States, and with the very concept of convoy itself. Axis submarines sank more than 3 million tons of Allied shipping between December 1941 and June 1942, well over 75 percent of it along the East Coast of the United States and Canada. Nevertheless, by mid-1942 an elaborate and comprehensive system of interlocking convoy routes and sailings was established for the East Coast of North America and the Caribbean.

As Dönitz became aware of the extension of convoy along the Atlantic East Coast, he shifted U-boat operations back to the mid-Atlantic. His all-out assault on the North Atlantic convoy systems inflicted heavy losses: between July 1942 and March 1943, Axis (almost entirely German) submarines destroyed more than 4.5 millions tons of Allied shipping, over 633,000 tons in March alone. Nevertheless, new Allied countermeasures became available at this crucial moment, and U-boat successes fell to 287,137 tons in April, 237,182 tons in May, and only 76,090 tons in June. Dönitz’s reaction was to deploy his U-boats in areas where Allied antisubmarine forces were weak, anticipating that this would compensate for the lack of success in the North Atlantic. Initially this plan to some extent met his expectations, since sinkings rose to 237,777 tons in J u l y, but the success of the Allied assault on U-boats in transit to their patrol stations rendered the German accomplishment transitory; merchant ship sinkings dropped to 92,443 tons in August, never to surpass 100,000 tons per month at any subsequent time during the war.

The collapse of the U-boat offensive in mid-1943 resulted from the Allies ‘ concurrent deployment of a series of new countermeasures and technologies that reached maturity almost simultaneously: centrimetric radar aboard both ships and aircraft, efficient shipborne high-frequency direction finding, ahead-throwing weapons that permitted ships to fire antisubmarine bombs forward and thus retain sonar contact, very-long-range shorebased antisubmarine aircraft, escort carriers and escort support groups, and advances in decryption of German communications codes. The U-boat arm attempted to defeat these countermeasures by deploying its own new weaponry, the most important elements of which were radar warning receivers, heavy antiaircraft batteries, and acoustic torpedoes designed to hunt antisubmarines vessels. Not only did these fail to stem the tide of Allied success against the U-boats, but new convoy communications codes also defeated German cryptographers, rendering locating targets much more difficult. Then, in 1944, Allied military successes in France began to force German U-boats to make more extended passages to their patrol areas as their home ports moved farther from the Atlantic; German air bases also ceased to give aircraft quick access to British coastal waters.

During the final year of this conflict, U-boats equipped with snorkels entered service. The production of new, fast elektroboote (the radical new Type XXI submarines with high underwater speed) allowed the first examples to become operational, but their numbers were far too few to make any difference. Also, there were insufficient experienced crews available to exploit their potential. Such was the success of Allied antisubmarine measures during this period that full-scale convoying became unnecessary in some areas, and much of the focus of their escorts turned to hunting U-boats rather than directly protecting merchant shipping. The full measure of the defeat of the U-boats is indicated by the fact that more than two-thirds of the 650 German submarines lost during World War II were sunk in the last two years of the war.

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