U-boat

Last updated

U-995, a typical VIIC/41 U-boat on display at the Laboe Naval Memorial U995 2001 1.jpg
U-995, a typical VIIC/41 U-boat on display at the Laboe Naval Memorial

U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. The term is an anglicised version of the German word U-Boot [ˈuːboːt] , a shortening of Unterseeboot (under-sea boat), though the German term refers to any submarine. Austro-Hungarian Navy submarines were also known as U-boats.

Contents

U-boats are most known for their unrestricted submarine warfare in both world wars, trying to disrupt merchant traffic towards the UK and force the UK out of the war. In World War I, Germany intermittently waged unrestricted submarine warfare against the UK: a first campaign in 1915 was abandoned after strong protests from the US but in 1917 the Germans, facing deadlock on the continent, saw no other option than to resume the campaign in February 1917. The renewed campaign failed to achieve its goal mainly because of the introduction of convoys. Instead the campaign ensured final defeat as the campaign was a contributing factor to the entry of the US in the First World War. [1]

In World War II, Karl Dönitz, supreme commander of the Kriegsmarine 's U-boat arm ( Befehlshaber der Unterseeboote), was convinced the UK and its convoys could be defeated by new tactics, and tried to focus on convoy battles. [2] Though U-boat tactics initially saw success in the Battle of the Atlantic, greatly disrupting Allied shipping, improved convoy and anti-submarine tactics such as high-frequency direction finding and the Hedgehog anti-submarine system began to take a toll on the German U-boat force. This ultimately came to a head in May 1943, known as Black May, in which U-boat losses began to outpace their effect on shipping.

Early U-boats (1850–1914)

The first German submarine, the SM U-1. SM U 1 800px.jpg
The first German submarine, the SM U-1.

The first submarine built in Germany, the three-man Brandtaucher , sank to the bottom of Kiel Harbor on 1 February 1851 during a test dive. [3] [4] Inventor and engineer Wilhelm Bauer had designed this vessel in 1850, and Schweffel and Howaldt constructed it in Kiel. Dredging operations in 1887 rediscovered Brandtaucher; she was later raised and put on historical display in Germany. The boats Nordenfelt I and Nordenfelt II, built to a Nordenfelt design, followed in 1890. In 1903, the Friedrich Krupp Germaniawerft dockyard in Kiel completed the first fully functional German-built submarine, Forelle , [5] which Krupp sold to Russia during the Russo-Japanese War in April 1904. [6]

At the beginning of the century, the German commander of the Navy Alfred von Tirpitz was building the High Seas Fleet with which he intended to challenge the supremacy of the Royal Navy. He focused on expensive battleships and there was no role for submarines in his fleet. Only when Krupp exported its submarines to Russia, Italy, Norway and Austria-Hungary did Tirpitz order one submarine. [7] The SM U-1 was a completely redesigned Karp-class submarine and when the Imperial German Navy commissioned it on 14 December 1906, [8] it was the last major navy to possess submarines. [7] The U-1 had a double hull and a single torpedo tube. It used an Electric motor powered by batteries for submerged propulsion and a Körting kerosene engine for charging the batteries and propulsion on the surface. The 50%-larger SM U-2 (commissioned in 1908) had two torpedo tubes.

The German submarine U-14, showing the kerosene vapour trail. SM U 11 800px.jpg
The German submarine U-14, showing the kerosene vapour trail.

Because speed and range were severely limited underwater while running on battery power, U-boats were required to spend most of their time surfaced, running on fuel engines, diving only when attacked or for torpedo strikes. The more ship-like hull design reflects the fact that these were primarily surface vessels that could submerge when necessary. This contrasts with the cylindrical profile of modern nuclear submarines, which are more hydrodynamic under water (where they spend the majority of their time), but less stable on the surface. While U-boats were faster on the surface than submerged, the opposite is generally true of modern submarines.

Between 1908 and 1910 fourteen big boats with four torpedo tubes and two reload torpedoes were ordered. These boats used a kerosene engine which was safer than gasoline and more powerful than steam, but the white exhaust of the kerosene betrayed the presence of the U-boats, robbing them of their primary asset, their stealth. Diesel engines did not have that disadvantage, but a powerful and reliable diesel engine was still under development. Finally the U-19 class of 1912–13 had the first diesel engine installed in a German navy boat. Between 1910 and 1912 twenty-three diesel U-boats were ordered. [9] At the start of World War I in 1914, Germany had 48 submarines of 13 classes in service or under construction. During that war, the Imperial German Navy used SM U-1 for training. Retired in 1919, she remains on display at the Deutsches Museum in Munich. [10]

World War I (1914–1918)

Sea mines are loaded in a UC coastal submarine in the harbour of Zeebrugge THE IMPERIAL GERMAN NAVY'S FLANDERS FLOTILLA DURING THE FIRST WORLD WAR Q20345.jpg
Sea mines are loaded in a UC coastal submarine in the harbour of Zeebrugge

Operations

During 1914, the U-boats operated against the British fleet: on 5 September 1914, the light cruiser HMS Pathfinder was sunk by SM U-21, the first ship to have been sunk by a submarine using a self-propelled torpedo. On 22 September, U-9 sank the armoured cruisers HMS Aboukir, HMS Cressy, and HMS Hogue. As a result, the British Grand Fleet had to withdraw to safer waters in Northern Ireland. Against merchant ships, U-boats observed the "prize rules" which meant they had to stop and inspect the ship, and take the crew off the ship before they could sink it. On 20 October 1914, SM U-17 sank the first merchant ship, SS Glitra, off Norway. Only ten merchants were sunk in that way before policy was changed on 18 February 1915. On the continent German hopes for a quick victory were dashed and a stalemate had settled on the front. The Germans hoped to break the deadlock by starting an unrestricted submarine campaign against shipping in the waters around the British Isles. This was also cited as a retaliation for British minefields and shipping blockades. Under the instructions given to U-boat captains, they could sink merchant ships, even neutral ones, without warning. [11]

Only 29 U-boats were available for the campaign, and not more than seven were active around the British Isles at any time. The U-boats failed to enforce a blockade but on the other hand three sinkings of liners with loss of American lives, outraged the US so that the Kaiser had to stop the campaign in September 1915: on 7 May 1915, SM U-20 sank RMS Lusitania, on 19 August, SM U-24 sank SS Arabic and on 9 September RMS Hesperian was sunk by SM U-20. Most of the U-boats were sent to the Mediterranean. At the beginning of 1916 54 U-boats were available, and the Kaiser allowed again operations around the British Isles, but with strict rules: no attacks on liners and outside the war zone around the British Isles attacks were only allowed on armed merchant ships. But on 24 March 25 Americans were killed in the torpedoing of the ferry SS Sussex, which was mistaken for a troopship by SM UB-29. The U.S. threatened to sever diplomatic ties, which persuaded the Germans to fully reapply prize rules. In September 1916 120 U-boats were in service, and again some were sent to the Mediterranean. Whilst around British Isles prize rules were observed, in the Mediterranean a new unrestricted campaign was started. The renewed German campaign was effective, sinking 1.4 million tons of shipping between October 1916 and January 1917. Despite this, the deadlock situation on the continent frontlines demanded even greater results, and on 1 February 1917, Germany restarted the unrestricted submarine campaign around British Isles. Germany took the gamble that the U-boat campaign would force the UK out of the war before the US could effectively enter. On 3 February the US severed diplomatic relations with Germany and on 6 April the U.S. declared war on Germany. [12]

German U-boat losses
Surface warships
55
Mines
48
Submarines
18
Q-ships
11
Merchant ships
7
Aircraft
1
Accidents
19
Unknown
19
Total
178

Unrestricted submarine warfare in 1917 was very successful, sinking more than 500,000 tons a month. With the introduction of convoys in August 1917 shipping losses declined to 300,000 a month on average, which was not sufficient to force the UK out of the war. With deteriorating conditions on the continent, all U-boats were recalled on 31 October 1918. [13] An armistice became effective on 11 November 1918. Under the terms of armistice, all U-boats were to immediately surrender. Those in home waters sailed to the British submarine base at Harwich, after which the vessels were studied, then scrapped or given to Allied navies. Stephen King-Hall wrote a detailed eyewitness account of the surrender. [14]

Of the 373 German U-boats that had been built, 179 were operational or nearly operational at the end of the war. 178 were lost by enemy action. [15] 512 officers and 4894 enlisted men were killed. Of the surviving German submarines, 14 U-boats were scuttled and 122 surrendered. [16] They sank 10 pre-dreadnought battleships, 18 heavy and light cruisers, and several smaller naval vessels. They further destroyed 5,708 merchant and fishing vessels for a total of 11,108,865 tons and the loss of about 15,000 sailors. [16]

The Pour le Mérite, the highest decoration for gallantry for officers, was awarded to 29 U-boat commanders.[ citation needed ] Twelve U-boat crewmen were decorated with the Goldenes Militär-Verdienst-Kreuz, the highest bravery award for noncommissioned officers and enlisted men. [17] The most successful U-boat commanders of World War I were Lothar von Arnauld de la Perière (189 merchant vessels and two gunboats with 446,708 tons), followed by Walter Forstmann (149 ships with 391,607 tons), and Max Valentiner (144 ships with 299,482 tons). Their records have not been surpassed in any subsequent conflict.

Classes

Körting kerosene-powered boats Type U 1, Type U 2, Type U 3, Type U 5, Type U 9, Type U 13, Type U 16, Type U 17
Mittel-U MAN diesel boats Type U 19, Type U 23, Type U 27, Type U 31, Type U 43, Type U 51, Type U 57, Type U 63, Type U 66, Type Mittel U
U-Cruisers and Merchant U-boats Type U 139, Type U 142, Type U 151, Type UD 1
UB coastal torpedo attack boats Type UB I, Type UB II, Type UB III, Type UF, Type UG
UC coastal minelayers Type UC I, Type UC II, Type UC III
UE ocean minelayers Type UE I, Type UE II

Interwar years (1919–1939)

The Finnish submarine Vetehinen in 1930 on the slipways at the Crichton-Vulcan shipyard in Turku, Finland Vetehinen-Crichton-Vulcan-1930.jpg
The Finnish submarine Vetehinen in 1930 on the slipways at the Crichton-Vulcan shipyard in Turku, Finland

Construction

The Treaty of Versailles ending World War I signed at the Paris Peace Conference in 1919 limited the surface navy of Germany's new Weimar Republic to only six battleships, six cruisers, twelve destroyers and twelve torpedo boats. The treaty also restricted the independent tonnage of ships and forbade the construction of submarines. [18] In order to circumvent the restrictions of the treaty, a submarine design office called Ingenieurskantoor voor Scheepsbouw (IVS) was set up in the Netherlands [19] The IVS was run by Krupp and made it possible to maintain a lead in submarine technology by designing and constructing submarines in Holland for other nations. [20] The IVS made designs for small 250-ton U-boats, medium 500-ton U-boats and large 750-ton U-boats. [21]

The IVS constructed three 500-ton medium submarines in Finland between 1927 and 1931, known as the Vetehinen-class. These ships were the prototypes for the subsequent German Type VII U-boat. In 1933 a small 250-ton submarine, the Vesikko. This submarine was nearly identical to the subsequent German Type II U-boat. A fifth very small 100-ton submarine, the Saukko was built in 1933 as well. In Spain a large 750-ton boat was built between 1929 and 1930. After the Spanish lost interest in the U-boat, they sold it to Turkey where it entered service as Gür. German sailors assisted in the trials for these submarines. These secret programs were exposed in by the Lohmann Affair and as a result the Head of the Reichsmarine Hans Zenker had to resign. His successor Erich Raeder continued the policy of secretly breaching the Versailles treaty. On 15 November 1932 a plan was approved for an expansion of the German navy which included U-boats. [22]

The Spanish submarine E-1 in Cadiz U-boot E-1.png
The Spanish submarine E-1 in Cadiz
U-534, a type IX U-boat at Birkenhead Docks, Merseyside, England U534.jpg
U-534, a type IX U-boat at Birkenhead Docks, Merseyside, England

In 1935, Britain sought to control the increasingly apparent breaches of the Versailles Treaty and it concluded in 1935 the Anglo-German Naval Agreement. This ended officially the limitation of the Versailles Treaty and allowed Germany to build ships in a 100:35 tonnage ratio to the British fleet. For submarines the Germans obtained a parity in tonnage, but promised a 45 percent limit unless special circumstances arose. [23] This allowed 24,000 tons for U-boat building. Only one week after the signature of the agreement, the first of six Type II U-boats, U-1 was commissioned in the German Navy, which changed name from Reichsmarine (State Navy) to Kriegsmarine (War Navy). [24] Within the year, the Germans commissioned a total of 36 U-boats for a total of 12,500 tons: [25]

Karl Dönitz was appointed as head of the submarine section of the kriegsmarine. He believed firmly that in spite of the Anglo-German Naval agreement and Hitler's policy of avoiding conflict with Britain, the next war would be with Britain. Based on these views he requested that the remaining 11,500 tons be used for building twenty-three medium submarines, which were in his opinion the ideal type for the commerce war against British convoys. Raeder however did not share these beliefs and opinions and opted for a more balanced expansion of the submarine fleet: [25]

Twenty-one of these twenty-three U-boats were commissioned before the start of World War II. In 1937 Britain announced it would expand its submarine fleet from 52,700 to 70,000 tons. Again, Raeder decided that the extra 7,785 tons would be divided between medium and large U-boats: [27]

A type XB submarine sinking in the Atlantic. On the foredeck the vertical mineshafts are visible. 80-G-700007 Battle of the Atlantic. German Submarine U-233 sinking after being rammed by USS Thomas (DE 102).jpg
A type XB submarine sinking in the Atlantic. On the foredeck the vertical mineshafts are visible.

During 1938 Hitler changed his attitude towards Britain. Whilst he still hoped that Britain would not interfere in his foreign policy it became clear to him that he needed a Navy that could act as a deterrent. Hitler wanted to invoke the escape clause of the naval agreement and to have 70,000 tons of submarines. Between May 1938 and January 1939 Raeder ordered 52 more U-boats, to be completed by 1942: [28]

In 1939, the ambitious Plan Z was launched. It called for the construction of a German Navy capable of challenging the Royal Navy. The plan included 249 U-boats for a total of 200,000 tons. But when World War II broke out only months after the plan was announced, only a handful of the planned U-boats ended up being built. [28]

When World War II started, Germany had 56 U-boats commissioned, of which 46 were operational and only 22 had enough range for Atlantic operations, the other 24 were limited to operations on the North Sea. [29]

Developments

A torpedo is loaded into a U-Boat through a torpedo hatch. Bundesarchiv Bild 101II-MW-5536-01, Wilhelmshaven, U-Boot, Torpedo-Ubernahme.jpg
A torpedo is loaded into a U-Boat through a torpedo hatch.

Compared to their World War I equivalents, the German U-boat designs of World War II were greatly improved. By using a new steel alloy and by welding instead of riveting they had stronger hulls and could dive deeper. The diving time was decreased to thirty seconds for a medium U-boat. The power of diesel engines was increased so U-boats had a greater surface speed. Range was increased by installing fuel saddle tanks, which were on the bottom open to the sea in order to balance pressure, and the diesel was floating freely on the seawater in the saddle tank. Also a technique was developed for economical cruising where only one of the two diesel engines was running and driving the two propeller shaft through a coupling with the two electro engines. [30]

Another vast improvement was the introduction of new torpedo types for the U-boats : the classic G7a torpedo propulsed with compressed air had a much larger warhead than its WWI equivalent, but more important was the introduction of the electric G7e torpedo. [31] This torpedo was slower and had less range but it left no telltale bubble wake and was hence ideally suited for daylight attacks. [30] During WWI the Germans had briefly experimented with magnetic pistols and these were further developed now as the standard pistol for torpedoes. The classic contact pistol required a torpedo to detonate against the ship side hull, whilst a magnetic torpedo could detonate below a ship, resulting in a much more damaging explosion. It was hoped that one torpedo would hence suffice to break the back of a ship and a U-boat could sink many more ships with its supply of torpedoes. [32] [33]

All U-boats were now also equipped with long- and short wave transmitters, which enabled to communicate with bases ashore and fellow U-boats at sea. This allowed for better operational information and guidance. [32]

U-Boat design and layout

Cross-section of a Type VII U-boat VIIC uboat shaded.svg
Cross-section of a Type VII U-boat

From bow to stern, A typical U-boat design comprised these sections:

World War II (1939–1945)

Operations

During World War II, U-boat warfare was the major component of the Battle of the Atlantic, which began in 1939 and ended with Germany's surrender in 1945. British Prime Minister Winston Churchill later wrote "The only thing that really frightened me during the war was the U-boat peril." [38] Cross-Atlantic trade in war supplies and food was extensive and critical for Britain's survival. The continuous action surrounding Allied shipping became known as the Battle of the Atlantic.

U-boat pens in Saint-Nazaire, France Base ssmarin stnazaire.jpg
U-boat pens in Saint-Nazaire, France

As convoying had been key in the defeat of German submarines during World War I, the British began organizing convoys at once in September 1939. The most common U-boat attack against convoys during the early years of the war was conducted on the surface and at night. During 1939 the Germans made a few attempts to attack convoys with their new 'wolfpack' tactic, but these were not successful. The invasion of Norway in April 1940 halted temporarily all U-boat operations against merchant shipping. During the invasion many technical problems with the German torpedoes were exposed and only in August 1940 could the campaign against convoys be revived. There were now fewer U-boats operational than at the beginning of the war, but thanks to the new bases in France and Norway U-boats could reach their operation grounds far more easily. During the following months the U-boats put their 'wolfpack' tactic against convoy in practice with spectacular results. This period, before the Allied forces developed truly effective antisubmarine warfare tactics, was referred to by German submariners as "die glückliche Zeit" or the First Happy Time. [39]

In the beginning of 1941 British countermeasures began to take effect: in March 1941 the three leading U-boat aces were sunk during convoy battles. In May 1941 the British were able to break into German secret naval Enigma communications and could henceforth reroute convoys around U-boat concentrations. [40] When American warships started to escort Atlantic convoys, the U-boats were restricted in their operations as Hitler wanted to avoid possible conflict with the US. [41] The campaign against merchant shipping received further impediments when Hitler interfered on two occasions: first he insisted that a small force of U-boats be kept on station in the Arctic as a precaution against a possible Allied invasion in Norway [42] [43] and next he ordered a substantial force of U-boats to operate in the Mediterranean in order to support the Italians and Rommel's Afrika Korps. [44]

When the US entered war, the focus of U-boat operations shifted to the Atlantic coast of the United States and Canada, where no convoys were organized and anti-submarine measures were inadequate. There followed a Second Happy Time when U-boats could extend their successful operation to the Gulf of Mexico and the Caribbean Sea. [45] By mid 1942 an adequate defense was organized in these regions and then U-boats returned to their original and crucial hunting grounds on the North Atlantic convoy lanes. [46] The renewed offensive against convoys reached its climax in March 1943, when two thirds of all ships sunk, were ships sailing in convoys. [47] But the Allies put effective countermeasures into effect and only two months later on 24 May Dönitz had to stop the campaign due to heavy losses. [48]

U-boats operated also off the southern African coasts and even as far east as the Arabian Sea and Indian Ocean.

By the end of the war, almost 3,000 Allied ships (175 warships; 2,825 merchant ships) had been sunk by U-boat torpedoes. [49] In total 1131 U-boats entered service before the German surrender, of which 863 have executed war patrols, and 785 were lost. [50] [51] Of the 154 U-boats surrendered, 121 were scuttled in deep water off Lisahally, Northern Ireland, or Loch Ryan, Scotland, in late 1945 and early 1946 during Operation Deadlight.

Torpedo developments

The U-boats' main weapon was the torpedo, though mines and deck guns (while surfaced) were also used. Early German World War II torpedoes were fitted with one of two types of pistol triggers – impact, which detonated the warhead upon contact with a solid object, and magnetic, which detonated upon sensing a change in the magnetic field within a few meters. Initially, the depth-keeping equipment and magnetic and contact exploders were notoriously unreliable. During the first eight months of the war, torpedoes often ran at an improper depth, detonated prematurely, or failed to explode altogether sometimes bouncing harmlessly off the hull of the target ship. This was most evident in Operation Weserübung, the invasion of Norway, where various skilled U-boat commanders failed to inflict damage on British transports and warships because of faulty torpedoes. The faults were largely due to a lack of testing. The magnetic detonator was sensitive to mechanical oscillations during the torpedo run, and to fluctuations in the Earth's magnetic field at high latitudes. These early magnetic detonators were eventually phased out. The depth-keeping problem remained problematic, not until January 1942 was the last fault discovered by accident: when ventilating the onboard torpedoes during maintenance, it was possible that the excess internal air-pressure in the U-boat offset the depth setting mechanism in the balance chamber of the torpedo. [52] [53]

The pattern running of a FAT torpedo Flachenabsuchender Torpedo type I-firing positions.svg
The pattern running of a FAT torpedo

In order to give U-boats better opportunities against well-defended convoys, several types of "pattern-running" torpedoes were developed. The FAT (Flächen-Absuch-Torpedo or Federapparat-Torpedo) and LUT (LageUnabhängiger Torpedo) was an electric torpedo which ran straight out to a preset distance, then traveled in either a circular or ladder-like pattern through the convoy lanes. This increased the probability of a hit. The torpedo had one setting to regulate the length of the prerun, after which one of four other possible settings kicked in and made the torpedo zigzag towards either left or right and either on short (1200 m) or long (1900 m) legs. When fired, the firing U-boat sent out a warning to the other U-boats in the vicinity so these could dive to avoid being hit by the random running torpedo. The FAT torpedo became available end of 1942 and was in regular use during the convoy battles of March 1943. [54] [55]

Germany also developed acoustic homing torpedoes. In February 1943 the first acoustic torpedo, the T4 "Falke", was tested on a small scale with moderate success, but this torpedo could only be used against large, slow ships. The acoustic torpedo ran straight to an arming distance of 1000 m and then turned toward the loudest noise detected. Its successor, the T5 "Zaunkönig", was designed to combat small and fast warships, and entered service in September 1943. [56] The Allies countered acoustic torpedoes with noisemaker decoys such as Foxer , FXR, CAT, and Fanfare.

U-boat developments

A prefabricated segment of a Type XXI U-boat. The cross-section shows clearly the '8'-shaped hull, where the lower part was used to store large batteries hence the name of 'ElektroBoot' Type XXI section.jpg
A prefabricated segment of a Type XXI U-boat. The cross-section shows clearly the '8'-shaped hull, where the lower part was used to store large batteries hence the name of 'ElektroBoot'

In 1940 the Germans made successful tests with the V-80 experimental submarine featuring a new type of propulsion: on the surface it used the classic Diesel engines but submerged it used a revolutionary hydrogen peroxide air-independent propellant system designed by Hellmuth Walter. With this Walter-turbine a U-boat could achieve underwater speeds of more than 20 knots, much more than the 4 knot cruising and 6 knot maximum speed of electrical engines powered by batteries. Four more experimental Type XVIIA U-boats with Walter turbines were built and tested, but the Germans could not put this design in use for a big frontline U-boat. [57] [58] Unlike a classic U-boat that could recharge its batteries with the diesel engines, once a Walter U-boat had consumed its hydrogen peroxide propellant it could not submerge anymore. The Germans did not possess the resources and plants to produce sufficient hydrogen peroxide to operate a fleet of Walter submarines. Despite these limitations, 24 frontline Type XVIIB coastal submarines were ordered, but only three were built and none were operational before the end of the war. [59]

The Walter U-boats had very large hulls in order to store the fuel for submerged propulsion. Once it became clear these Walter U-boats would not be operational in time, the Walter U-boat hull design was reused with a different approach : the space for the hydrogen peroxide tanks was used to store much larger batteries. With the much increased battery power U-boats were also able to reach much higher speeds and endurance when submerged. [60] Based on the design of an Atlantic Walter U-boat, the Type XXI "Elektroboot" was designed to boost submerged performance. A smaller Type XXIII coastal Elektroboote was also taken into production. These Elektroboote were mass-produced, with prefabricated segments constructed at different sites and then assembled at the bigger shipyards. [61] [62]

The Schnorkel
mast and air flows Submarine snorkel.png
The Schnorkel mast and air flows

After the German invasion of the Netherlands in 1940 the Germans captured some Dutch submarines equipped with a Schnorchel (snorkel), but saw no need for them until 1943. The Schnorchel was a retractable pipe that supplied air to the diesel engines while submerged at periscope depth, allowing the boats to cruise submerged on diesel engines and recharge their batteries. [63] It was far from a perfect solution: problems occurred with the device's valve sticking shut or closing as it dunked in rough weather; since the system used the entire pressure hull as a buffer, the diesels would instantaneously suck huge volumes of air from the boat's compartments, and the crew often suffered painful ear injuries. Speed was limited to 8 knots (15 km/h), lest the device snap from stress. Whilst running submerged with the Schnorchel, the Gruppenhorchgerät was useless because of interference with the noisy diesel engines. But the Schnorchel allowed the old Type VII and IX U-boats to operate in waters which were previously denied to them. [64] Finally, Allied radar eventually became sufficiently advanced that the Schnorchel mast could be detected.

Classes

Countermeasures

Throughout the war, an arms race evolved between the Allies and the Kriegsmarine. Sonar (ASDIC in Britain) allowed Allied warships to detect submerged U-boats, but was not effective against a surfaced vessel; thus, early in the war, a U-boat at night or in bad weather was actually safer on the surface. Advancements in radar became deadly for the U-boat crews, especially once aircraft-mounted units were developed. As a countermeasure, U-boats were fitted with radar warning receivers, to give them ample time to dive before the enemy closed in, as well as more antiaircraft guns, but by early to mid-1943, the Allies switched to centimetric radar (unknown to Germany), which rendered the radar detectors ineffective. U-boat radar systems were also developed, but many captains chose not to use them for fear of broadcasting their position to the enemy. Against ASDIC the Germans developed Bold, a chemical bubble-making decoy.

Advances in convoy tactics, high-frequency direction finding, referred to as "Huff-Duff", radar, sonar, depth charges, anti-submarine weapons such as "Hedgehog" and "FIDO", the intermittent cracking of the German Naval Enigma code, the introduction of the Leigh Light, long range patrol aircraft, escort carriers and the enormous US shipbuilding capacity, all turned the tide against the U-boats. At the same time, the Allies targeted the U-boat shipyards and their bases with strategic bombing.

Captured Type VII and Type IX U-boats outside their pen in Trondheim, Norway, 19 May 1945 Captured German U-boats outside their pen at Trondheim in Norway, 19 May 1945. BU6382.jpg
Captured Type VII and Type IX U-boats outside their pen in Trondheim, Norway, 19 May 1945

In May 1941 code books, an Enigma machine and its settings were captured from the U-110 which could be boarded before she sank. A team including Alan Turing used special-purpose "Bombes" and early computers to break new German codes as they were introduced. The speedy decoding of messages allowed rerouting convoys around U-boat patrol lines. In February 1942 the naval Enigma machines were altered and this advantage was lost until the new code was broken in October 1942, when U-559 was boarded as she was sinking, and crucial code books were salvaged.

Post–World War II and Cold War (after 1945)

U-15 and U-17, Type 206 submarines, of the German Navy Submarines S194 and S196.jpg
U-15 and U-17, Type 206 submarines, of the German Navy

From 1955, the West German Bundesmarine was allowed to have a small navy. Initially, two sunken Type XXIIIs and a Type XXI were raised and repaired. In the 1960s, the Federal Republic of Germany (West Germany) re-entered the submarine business. Because West Germany was initially restricted to a 450-tonne displacement limit, the Bundesmarine focused on small coastal submarines to protect against the Soviet threat in the Baltic Sea. The Germans sought to use advanced technologies to offset the small displacement, such as amagnetic steel to protect against naval mines and magnetic anomaly detectors.

The initial Type 201 was a failure because of hull cracking; the subsequent Type 205, first commissioned in 1967, was a success, so 12 were built for the German navy. To continue the U-boat tradition, the new boats received the classic "U" designation starting with the U-1.

With the Danish government's purchase of two Type 205 boats, the West German government realized the potential for the submarine as an export, developing a customized version Type 207. Small and agile submarines were built during the Cold War to operate in the shallow Baltic Sea, resulting in the Type 206. Three of the improved Type 206 boats were later sold to the Israeli Navy, becoming the Type 540. The German Type 209 diesel-electric submarine was the most popular export-sales submarine in the world from the late 1960s into the first years of the 21st century. With a larger 1,000–1,500 tonne displacement, the class was very customizable and has seen service with 14 navies, with 51 examples being built as of 2006. Germany continued to reap successes with derivations or on the basis of the successful type 209, as are the Type 800 sold to Israel and the TR-1700 sold to Argentina.

Germany continued to succeed as an exporter of submarines as the Klasse 210 sold to Norway, considered the most silent and maneuverable submarines in the world. This demonstrated its capacity and put its export seal on the world.

Type 212 submarine with air-independent propulsion of the German Navy in dock at HDW/Kiel U Boot 212 HDW 1.jpg
Type 212 submarine with air-independent propulsion of the German Navy in dock at HDW/Kiel

Germany has brought the U-boat name into the 21st century with the new Type 212; it 212 features an air-independent propulsion system using hydrogen fuel cells. This system is safer than previous closed-cycle diesel engines and steam turbines, cheaper than a nuclear reactor, and quieter than either. While the Type 212 is also being purchased by Italy [65] and Norway, [66] the Type 214 has been designed as the follow-on export model and has been sold to Greece, South Korea, and Turkey, and based on it would get the Type U 209PN sold to Portugal.

In recent years Germany introduced new models such as the Type 216 and the Type 218, the latter being sold to Singapore.

In 2016, Germany commissioned its newest U-boat, the U-36, a Type 212.

See also

Citations

  1. Blair, pp. 10–19.
  2. Blair, pp. 38–39.
  3. Showell, p. 23.
  4. Chaffin, p. 53.
  5. Showell, p. 201.
  6. Showell, pp. 22–29.
  7. 1 2 Blair, p. 6.
  8. Showell, p. 30.
  9. Blair, p. 7.
  10. Showell, pp. 36–37.
  11. Blair, pp. 9–11.
  12. Blair, pp. 10–13.
  13. Blair, pp. 13–19.
  14. King-Hall, pp. 229–242.
  15. Blair, p. 18.
  16. 1 2 Clodfelter, p. 428.
  17. Fischer, p. 16.
  18. Humble, p. 25.
  19. Costello & Hughes, p. 26.
  20. Blair, p. 24.
  21. Blair, p. 31.
  22. Blair, pp. 31–32.
  23. Costello & Hughes, p. 28.
  24. Blair, pp. 34–35.
  25. 1 2 Blair, p. 40.
  26. 1 2 Paterson 2003, p. x-xi.
  27. Blair, p. 45.
  28. 1 2 Blair, pp. 46–47.
  29. Mason, p. 23.
  30. 1 2 Blair, p. 37.
  31. Bekker, p. 129.
  32. 1 2 Blair, p. 38.
  33. Bekker, p. 120.
  34. 1 2 3 4 5 Blair, pp. 57–59.
  35. Paterson, pp. 55–56.
  36. 1 2 Gannon, p. 34.
  37. 1 2 3 Blair, p. 62.
  38. Churchill, p. 529.
  39. "Military History Online". www.militaryhistoryonline.com. Retrieved 4 February 2019.
  40. Costello & Hughes, pp. 154–155.
  41. Costello & Hughes, p. 165.
  42. Blair, pp. 357–358.
  43. Mason, p. 68.
  44. Mason, p. 54.
  45. Mason, pp. 72–73.
  46. Blair, p. 654.
  47. Mason, p. 108.
  48. Rohwer, p. 252.
  49. Crocker III, H. W. (2006). Don't Tread on Me . New York: Crown Forum. p.  310. ISBN   978-1-4000-5363-6.
  50. Haskell, p. 14.
  51. Middlebrook, p. 327.
  52. Dönitz, p. 482.
  53. Blair, p. 485.
  54. Middlebrook, pp. 170–171.
  55. Brennecke 1984, pp. 389–391.
  56. Brennecke 1984, pp. 391–394.
  57. Blair Vol2, pp. 10–11.
  58. Costello & Hughes, pp. 284–285.
  59. Blair Vol2, p. 312.
  60. Breyer, pp. 7–13.
  61. Blair Vol2, pp. 312–313.
  62. Costello & Hughes, pp. 285–287.
  63. Breyer, p. 8.
  64. Costello & Hughes, p. 284.
  65. "Naval Technology on the Todaro class" . Retrieved 9 March 2019.
  66. Berg Bentzrød.

Related Research Articles

<span class="mw-page-title-main">Submarine</span> Watercraft capable of independent operation underwater

A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as boats rather than ships irrespective of their size.

Type XXI submarine German World War II submarine class

Type XXI submarines were a class of German diesel–electric Elektroboot submarines designed during the Second World War. One hundred and eighteen were completed, with four being combat-ready. During the war only two were put into active service and went on patrols, but these were not used in combat.

V-boat Group of U.S. Navy submarines and classes derived from them

The V-boats were a group of nine United States Navy submarines built between World War I and World War II from 1921 to 1934 under authorization as the "fleet boat" program.

German submarine <i>U-995</i> German World War II submarine

German submarine U-995 is a Type VIIC/41 U-boat of Nazi Germany's Kriegsmarine. She was laid down on 25 November 1942 by Blohm & Voss in Hamburg, Germany, and commissioned on 16 September 1943 with Oberleutnant zur See Walter Köhntopp in command. She is preserved at Laboe Naval Memorial near Kiel.

<span class="mw-page-title-main">Anti-submarine warfare</span> Branch of naval warfare

Anti-submarine warfare is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typically carried out to protect friendly shipping and coastal facilities from submarine attacks and to overcome blockades.

The history of the submarine goes back to antiquity. Humanity has employed a variety of methods to travel underwater for exploration, recreation, research and significantly, warfare. While early attempts, such as those by Alexander the Great, were rudimentary, the advent of new propulsion systems, fuels, and sonar, propelled an increase in submarine technology. The introduction of the diesel engine, then the nuclear submarine, saw great expansion in submarine use – and specifically military use – during World War I, World War II, and the Cold War. The Second World War use of the U-Boat by the Kriegsmarine against the Royal Navy and commercial shipping, and the Cold War's use of submarines by the United States and Russia, helped solidify the submarine's place in popular culture. The latter conflicts also saw an increasing role for the military submarine as a tool of subterfuge, hidden warfare, and nuclear deterrent. The military use of submarines continues to this day, predominantly by North Korea, China, the United States and Russia.

German submarine U-31 was a Type VIIA U-boat of Nazi Germany's Kriegsmarine during World War II. She was laid down on 1 March 1936 as yard number 912, launched on 25 September and commissioned on 28 December 1936.

SM <i>UB-46</i> German Imperial Navys Type UB II submarine

SM UB-46 was a Type UB II submarine or U-boat for the German Imperial Navy during World War I. UB-46 operated in the Mediterranean and the Black Seas, and was sunk by a mine in December 1916.

German submarine U-73 was a Type VIIB U-boat of Nazi Germany's Kriegsmarine during World War II. She was laid down by Vegesacker Werft, Germany as yard number 1 on 5 November 1939, launched on 27 July 1940 and commissioned on 30 September of the same year under Kapitänleutnant (Kptlt.) Helmut Rosenbaum.

German submarine U-402 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II.

<i>Balilla</i>-class submarine Submarine class of the Italian navy

The Balilla class were the first submarines to be built for the Italian navy following the end of World War I. They were large ocean-going cruiser submarines designed to operate in the Indian Ocean based in Italy's East African colonies. The design was double-hulled and based on the German Type UE 2 U-boats, one of which, U-120 was supplied to the Italians as a war reparation. A 425 horsepower (317 kW) auxiliary diesel engine was installed as an extra generator.

SM UB-44 was a Type UB II submarine or U-boat for the German Imperial Navy during World War I. UB-44 operated in the Mediterranean and disappeared in August 1916.

German submarine U-704 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.

SM <i>U-21</i> (Germany) U-boat built for the Imperial German Navy (1913)

SM U-21 was a U-boat built for the Imperial German Navy shortly before World War I. The third of four Type U-19-class submarines, these were the first U-boats in German service to be equipped with diesel engines. U-21 was built between 1911 and October 1913 at the Kaiserliche Werft in Danzig. She was armed with four torpedo tubes and a single deck gun; a second gun was added during her career.

German submarine U-705 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.

German submarine <i>U-55</i> (1939) German World War II submarine

German submarine U-55 was a Type VIIB U-boat of Nazi Germany's Kriegsmarine during World War II. She was ordered on 16 July 1937 and laid down on 2 November 1938 at Friedrich Krupp Germaniawerft in Kiel as yard number 590. Launched on 19 October 1939, she went into service on 21 November 1939 under the command of Kapitänleutnant (Kptlt.) Werner Heidel.

German submarine U-87 was a Type VIIB U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 18 April 1940 at the Flender Werke (yard) at Lübeck as yard number 283 and launched on 21 June 1941. She was commissioned on 21 June under the command of Kapitänleutnant Joachim Berger. U-87 trained with 6th U-boat Flotilla until 1 December 1941, when she was put on front-line service.

German submarine U-147 was a Type IID U-boat of the German Navy (Kriegsmarine) during World War II. She was laid down on 10 April 1940 at Deutsche Werke in Kiel as yard number 276, launched on 16 November 1940 and commissioned on 11 December under the command of Kapitänleutnant Reinhard Hardegen.

German submarine U-960 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 20 March 1942 by Blohm & Voss, Hamburg as yard number 160, launched on 3 December 1942 and commissioned on 28 January 1943 under Oberleutnant zur See Günther Heinrich.

German submarine U-457 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.

References

Further reading