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U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role ( commerce raiding) and enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
and other parts of the
British Empire The British Empire was composed of the dominions, colonies, protectorates, mandates, and other territories ruled or administered by the United Kingdom and its predecessor states. It began with the overseas possessions and trading posts e ...
, and from the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
, to the United Kingdom and (during the Second World War) to the Soviet Union and the Allied territories in the Mediterranean. German submarines also destroyed Brazilian merchant ships during World War II, causing Brazil to declare war on both Germany and Italy on 22 August 1942. The term is an
anglicised Anglicisation is the process by which a place or person becomes influenced by English culture or British culture, or a process of cultural and/or linguistic change in which something non-English becomes English. It can also refer to the influen ...
version of the German word ''U-Boot'' , a shortening of ''Unterseeboot'' ('under-sea-boat'), though the German term refers to any
submarine A submarine (or sub) 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 op ...
. Austro-Hungarian Navy submarines were also known as U-boats.


Early U-boats (1850–1914)

The first submarine built in Germany, the three-man ''
Brandtaucher ''Brandtaucher'' (German for ''Fire-diver'') was a submersible designed by the Bavarian inventor and engineer Wilhelm Bauer and built by Schweffel & Howaldt in Kiel for Schleswig-Holstein's Flotilla (part of the '' Reichsflotte'') in 1850 ...
'', sank to the bottom of
Kiel Kiel () is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 246,243 (2021). Kiel lies approximately north of Hamburg. Due to its geographic location in the southeast of the Jutland ...
harbor on 1 February 1851 during a test dive. The inventor and
engineer Engineers, as practitioners of engineering, are professionals who Invention, invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considerin ...
Wilhelm Bauer had designed this vessel in 1850, and Schweffel & Howaldt constructed it in
Kiel Kiel () is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 246,243 (2021). Kiel lies approximately north of Hamburg. Due to its geographic location in the southeast of the Jutland ...
. Dredging operations in 1887 rediscovered ''Brandtaucher''; it was later raised and put on historical display in Germany. There followed in 1890 the boats ''Nordenfelt I'' and ''Nordenfelt II'', built to a
Nordenfelt The Nordenfelt gun was a multiple-barrel organ gun that had a row of up to twelve barrels. It was fired by pulling a lever back and forth and ammunition was gravity fed through chutes for each barrel. It was produced in a number of different c ...
design. In 1903 the Friedrich Krupp Germaniawerft dockyard in Kiel completed the first fully functional German-built submarine, '' Forelle'', which Krupp sold to Russia during the
Russo-Japanese War The Russo-Japanese War ( ja, 日露戦争, Nichiro sensō, Japanese-Russian War; russian: Ру́сско-япóнская войнá, Rússko-yapónskaya voyná) was fought between the Empire of Japan and the Russian Empire during 1904 and 1 ...
in April 1904. The was a completely redesigned and only one was built. The
Imperial German Navy The Imperial German Navy or the Imperial Navy () was the navy of the German Empire, which existed between 1871 and 1919. It grew out of the small Prussian Navy (from 1867 the North German Federal Navy), which was mainly for coast defence. Wilhel ...
commissioned it on 14 December 1906. It had a double hull, a Körting
kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning " wax", and was re ...
engine, and a single torpedo tube. The 50%-larger (commissioned in 1908) had two torpedo tubes. The class of 1912–13 saw the first
diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-cal ...
installed in a German navy boat. 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, it remains on display at the
Deutsches Museum The Deutsches Museum (''German Museum'', officially (English: ''German Museum of Masterpieces of Science and Technology'')) in Munich, Germany, is the world's largest museum of science and technology, with about 28,000 exhibited objects from ...
in Munich.


World War I (1914–1918)

On 5 September 1914, was sunk by , the first ship to have been sunk by a submarine using a self-propelled torpedo. On 22 September, under the command of Otto Weddigen sank the obsolete British warships , and (the "
Live Bait Squadron The 7th Cruiser Squadron (also known as Cruiser Force C) was a blockading force of the Royal Navy during the First World War used to close the English Channel to German traffic. It was employed patrolling an area of the North Sea known as the ...
") in a single hour. In the Gallipoli Campaign in early 1915 in the eastern Mediterranean, German U-boats, notably the ''U-21'', prevented close support of allied troops by 18 pre-Dreadnought battleships by sinking two of them. For the first few months of the war, U-boat anticommerce actions observed the "prize rules" of the time, which governed the treatment of enemy civilian ships and their occupants. On 20 October 1914, sank the first merchant ship, the , off Norway. Surface commerce raiders were proving to be ineffective, and on 4 February 1915, the
Kaiser ''Kaiser'' is the German word for "emperor" (female Kaiserin). In general, the German title in principle applies to rulers anywhere in the world above the rank of king (''König''). In English, the (untranslated) word ''Kaiser'' is mainly ap ...
assented to the declaration of a war zone in the waters around the British Isles. This was cited as a retaliation for British minefields and shipping blockades. Under the instructions given to U-boat captains, they could sink merchant ships, even potentially neutral ones, without warning. In February 1915, a submarine ''U-6'' (''Lepsius'') was rammed and both periscopes were destroyed off Beachy Head by the collier SS ''Thordis'' commanded by Captain John Bell after firing a torpedo. On 7 May 1915, sank the liner RMS ''Lusitania''. The sinking claimed 1,198 lives, 123 of them American civilians, and the attack of this unarmed civilian ship deeply shocked the
Allies An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...
. According to the ship's manifest, ''Lusitania'' was carrying military cargo, though none of this information was relayed to the citizens of Britain and the United States who thought that the ship contained no ammunition or military weaponry whatsoever and it was an act of brutal murder. Munitions that it carried were thousands of crates full of ammunition for rifles, 3-inch (76 mm) artillery shells, and also various other standard ammunition used by infantry. The sinking of the ''Lusitania'' was widely used as propaganda against the German Empire and caused greater support for the war effort. A widespread reaction in the U.S was not seen until the attack on the ferry which carried many citizens of the United States of America. The initial U.S. response was to threaten to sever
diplomatic ties Diplomacy comprises spoken or written communication by representatives of states (such as leaders and diplomats) intended to influence events in the international system.Ronald Peter Barston, ''Modern diplomacy'', Pearson Education, 2006, p. 1 ...
, which persuaded the Germans to issue the
Sussex pledge The Sussex Pledge was a promise made by Germany to the United States in 1916, during World War I before the latter entered World War I. Early in 1915, Germany had instituted a policy of unrestricted submarine warfare, allowing armed merchant ship ...
that reimposed restrictions on U-boat activity. The U.S. reiterated its objections to German
submarine warfare Submarine warfare is one of the four divisions of underwater warfare, the others being anti-submarine warfare, mine warfare and mine countermeasures. Submarine warfare consists primarily of diesel and nuclear submarines using torpedoes, mis ...
whenever U.S. civilians died as a result of German attacks, which prompted the Germans to fully reapply prize rules. This, however, removed the effectiveness of the U-boat fleet, and the Germans consequently sought a decisive surface action, a strategy that culminated in the Battle of Jutland. Although the Germans claimed victory at Jutland, the British Grand Fleet remained in control at sea. It was necessary to return to effective anticommerce warfare by U-boats. Vice-Admiral Reinhard Scheer, Commander in Chief of the High Seas Fleet, pressed for all-out U-boat war, convinced that a high rate of shipping losses would force Britain to seek an early peace before the United States could react effectively. The renewed German campaign was effective, sinking 1.4 million tons of shipping between October 1916 and January 1917. Despite this, the political situation demanded even greater pressure, and on 31 January 1917, Germany announced that its U-boats would engage in
unrestricted submarine warfare Unrestricted submarine warfare is a type of naval warfare in which submarines sink merchant ships such as freighters and tankers without warning, as opposed to attacks per prize rules (also known as "cruiser rules") that call for warships to s ...
beginning 1 February. On 17 March, German submarines sank three American merchant vessels, and the U.S. declared war on Germany in April 1917. Unrestricted submarine warfare in early 1917 was initially very successful, sinking a major part of Britain-bound shipping. With the introduction of escorted convoys, shipping losses declined and in the end, the German strategy failed to destroy sufficient Allied shipping. An armistice became effective on 11 November 1918. Of the surviving German submarines 14 U-boats were scuttled and 122 surrendered. Of the 373 German submarines that had been built, 178 were lost by enemy action. Of these 40 were sunk by mines, 30 by depth charges and 13 by Q-ships. 512 officers and 4894 enlisted men were killed. They sank 10 battleships, 18 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. The
Pour le Mérite The ' (; , ) is an order of merit (german: Verdienstorden) established in 1740 by King Frederick II of Prussia. The was awarded as both a military and civil honour and ranked, along with the Order of the Black Eagle, the Order of the Red Eag ...
, the highest decoration for gallantry for officers, was awarded to 29 U-boat commanders. 12 U-boat crewmen were decorated with the Goldene Militär-Verdienst-Kreuz, the highest bravery award for non-commissioned officers and enlisted men. 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


Surrender of the fleet

Under the terms of armistice, all U-boats were to immediately surrender. Those in home waters sailed to the British submarine base at Harwich. The entire process was done quickly and in the main without difficulty, after which the vessels were studied, then scrapped or given to Allied navies.
Stephen King-Hall William Stephen Richard King-Hall, Baron King-Hall of Headley (21 January 1893 – 2 June 1966) was a British naval officer, writer, politician and playwright who served as the member of parliament for Ormskirk from 1939 to 1945. Early life and ...
wrote a detailed eyewitness account of the surrender.


Interwar years (1919–1939)

The
Treaty of Versailles The Treaty of Versailles (french: Traité de Versailles; german: Versailler Vertrag, ) was the most important of the peace treaties of World War I. It ended the state of war between Germany and the Allied Powers. It was signed on 28 June 1 ...
ending World War I signed at the Paris Peace Conference in 1919 restricted the total tonnage of the German surface fleet. The treaty also restricted the independent tonnage of ships and forbade the construction of submarines. However, a submarine design office was set up in the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
and a torpedo research program was started in Sweden. Before the start of World War II, Germany started building U-boats and training crews, labeling these activities as "research" or concealing them using other covers. When this became known, the Anglo-German Naval Agreement limited Germany to parity with Britain in submarines. When World War II started, Germany already had 65 U-boats, with 21 of those at sea, ready for war.


World War II (1939–1945)

During
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
, 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. The Armistice of 11 November 1918 ending
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
had scuttled most of the old
Imperial German Navy The Imperial German Navy or the Imperial Navy () was the navy of the German Empire, which existed between 1871 and 1919. It grew out of the small Prussian Navy (from 1867 the North German Federal Navy), which was mainly for coast defence. Wilhel ...
and the subsequent
Treaty of Versailles The Treaty of Versailles (french: Traité de Versailles; german: Versailler Vertrag, ) was the most important of the peace treaties of World War I. It ended the state of war between Germany and the Allied Powers. It was signed on 28 June 1 ...
of 1919 limited the surface navy of Germany's new
Weimar Republic The Weimar Republic (german: link=no, Weimarer Republik ), officially named the German Reich, was the government of Germany from 1918 to 1933, during which it was a Constitutional republic, constitutional federal republic for the first time in ...
to only six battleships (of less than 10,000 tons each), six cruisers, and 12
destroyer In naval terminology, a destroyer is a fast, manoeuvrable, long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers. They were originally developed ...
s. To compensate, Germany's new navy, the Kriegsmarine, developed the largest submarine fleet going into World War II. British Prime Minister
Winston Churchill Sir Winston Leonard Spencer Churchill (30 November 187424 January 1965) was a British statesman, soldier, and writer who served as Prime Minister of the United Kingdom twice, from 1940 to 1945 during the Second World War, and again from ...
later wrote "The only thing that really frightened me during the war was the U-boat peril." In the early stages of the war, the U-boats were extremely effective in destroying Allied shipping due to the large gap in mid-Atlantic air cover. Cross-Atlantic trade in war supplies and food was extensive and critical for Britain's survival. The continuous action surrounding British shipping became known as the Battle of the Atlantic, as the British developed technical defences such as ASDIC and
radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...
, and the German U-boats responded by hunting in what were called " wolfpacks" where multiple submarines would stay close together, making it easier for them to sink a specific target. Britain's vulnerable shipping situation existed until 1942, when the tides changed as the U.S. merchant marine and Navy entered the war, drastically increasing the amount of tonnage of supplies sent across the Atlantic. The combination of increased tonnage and increased naval protection of shipping convoys made it much more difficult for U-boats to make a significant dent in British shipping. Once the United States entered the war, U-boats ranged from the Atlantic coast of the United States and Canada to the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...
, and from the
Arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...
to the west and southern African coasts and even as far east as Penang. The U.S. military engaged in various tactics against German incursions in the Americas; these included military surveillance of foreign nations in Latin America, particularly in the Caribbean, to deter any local governments from supplying German U-boats. 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 diesel engines, diving only when attacked or for rare daytime 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 underwater (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. The most common U-boat attack during the early years of the war was conducted on the surface and at night. This period, before the Allied forces developed truly effective antisubmarine warfare tactics, which included convoys, was referred to by German submariners as "''die glückliche Zeit''" or the First Happy Time.


Torpedoes

The U-boats' main weapon was the
torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, ...
, though mines and deck guns (while surfaced) were also used. By the end of the war, almost 3,000 Allied ships (175 warships; 2,825 merchant ships) had been sunk by U-boat torpedoes. Early German World War II torpedoes were straight runners, as opposed to the homing and pattern-running torpedoes that became available later in the war. They 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. One of the most effective uses of magnetic pistols would be to set the torpedo's depth to just beneath the keel of the target. The explosion under the target's keel would create a detonation
shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...
, which could cause a ship's hull to rupture under the concussive water pressure. In this way, even large or heavily armored ships could be sunk or disabled with a single, well-placed hit. 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, and the depth-keeping problem was solved by early 1942 with improved technology. Later in the war, Germany developed an acoustic homing torpedo, the G7/T5. It was primarily designed to combat convoy escorts. The acoustic torpedo was designed to run straight to an arming distance of 400 m and then turn toward the loudest noise detected. This sometimes ended up being the U-boat; at least two submarines may have been sunk by their own homing torpedoes. Additionally, these torpedoes were found to be only effective against ships moving at greater than . The Allies countered acoustic torpedoes with noisemaker decoys such as ''
Foxer Foxer was the code name for a British built acoustic decoy used to confuse German acoustic homing torpedoes like the G7 torpedo during the Second World War. A US version codenamed FXR was deployed at the end of September 1943 on all transatlanti ...
'', ''FXR'', ''CAT'' and ''Fanfare''. The Germans, in turn, countered this by introducing newer and upgraded versions of the acoustic torpedoes, like the late-war G7es, and the T11. However, the T11 did not see active service. U-boats also adopted several types of "pattern-running" torpedoes that ran straight out to a preset distance, then traveled in either a circular or ladder-like pattern. When fired at a convoy, this increased the probability of a hit if the weapon missed its primary target.


U-boat developments

During World War II, the ''Kriegsmarine'' produced many different types of U-boats as technology evolved. Most notable is the Type VII, known as the "workhorse" of the fleet, which was by far the most-produced type, and the Type IX boats, an enlarged VII designed for long-range patrols, some traveling as far as Japan and the east coast of the United States. With the increasing sophistication of Allied detection and subsequent losses, German designers began to fully realise the potential for a truly submerged boat. The Type XXI "''Elektroboot''" was designed to favor submerged performance, both for combat effectiveness and survival. It was the first true submersible. The Type XXI featured an evolutionary design that combined several different strands of the U-boat development program, most notably from the Walter U-boats, the Type XVII, which featured an unsuccessful yet revolutionary
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3 ...
air-independent propellant system. These boats featured a streamlined hull design, which formed the basis of the later nuclear submarine, and was adapted for use with more conventional propulsion systems. The larger hull design allowed for a greatly increased battery capacity, which enabled the XXI to cruise submerged for longer periods and reach unprecedented submerged speeds for the time. Waste disposal was a problem when the U-boats spent extended periods without surfacing, as it is today. Throughout the war, an arms race evolved between the Allies and the ''Kriegsmarine'', especially in detection and counterdetection.
Sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...
(ASDIC in Britain) allowed Allied warships to detect submerged U-boats (and vice versa) beyond visual range, 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 Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...
became particularly 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 anti-aircraft guns. However, by early to mid-1943, the Allies switched to
centimetric radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weat ...
(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 enemy patrols and lack of sufficient electronic countermeasures. Early on, the Germans experimented with the idea of the ''Schnorchel'' (snorkel) from captured Dutch submarines, but saw no need for them until rather late in the war. The ''Schnorchel'' was a retractable pipe that supplied air to the diesel engines while submerged at periscope depth, allowing the boats to cruise and recharge their batteries while maintaining a degree of stealth. It was far from a perfect solution, however. 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 , lest the device snap from stress. The ''Schnorchel'' also had the effect of making the boat essentially noisy and deaf in sonar terms. Finally, Allied radar eventually became sufficiently advanced that the ''Schnorchel'' mast could be detected beyond visual range. Several other pioneering innovations included acoustic- and electro-absorbent coatings to make them less of an ASDIC or RADAR target. The Germans also developed active countermeasures such as facilities to release artificial chemical bubble-making decoys, known as '' Bold'', after the mythical
kobold A kobold (occasionally cobold) is a mythical sprite. Having spread into Europe with various spellings including " goblin" and "hobgoblin", and later taking root and stemming from Germanic mythology, the concept survived into modern times in G ...
.


Classes

* Type I: first prototypes * Type II: small submarines used for training purposes * Type V: uncompleted experimental midget submarines *
Type VII Type VII U-boats were the most common type of German World War II U-boat. 703 boats were built by the end of the war. The lone surviving example, , is on display at the Laboe Naval Memorial located in Laboe, Schleswig-Holstein, Germany. ...
: the "workhorse" of the U-boats with 709 completed in World War II *
Type IX The Type IX U-boat was designed by Nazi Germany's '' Kriegsmarine'' in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. Type IX boats were briefly used for patrols off the eastern U ...
: these long-range U-boats operated as far as the Indian Ocean with the Japanese (
Monsun Gruppe The ''Gruppe Monsun'' or Monsoon Group was a force of German U-boats (submarines) that operated in the Pacific and Indian Oceans during World War II. Although similar naming conventions were used for temporary groupings of submarines in the At ...
), and the
South Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe a ...
* Type X: long-range minelayers and cargo transports * Type XI: uncompleted experimental artillery boats * Type XIV: used to resupply other U-boats; nicknamed the ''Milchkuh'' ("Milk Cow") * Type XVII: small coastal submarines powered by experimental hydrogen peroxide propulsion systems * Type XXI: known as the ''Elektroboot''; first subs to operate primarily submerged * Type XXIII: smaller version of the XXI used for coastal operations *
Midget submarine A midget submarine (also called a mini submarine) is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to six or nine, with little or no on-board living accommodation. They normally work with mother ships, ...
s, including ''Biber'', ''Hai'', '' Molch'', and '' Seehund'' * Uncompleted U-boat projects


Countermeasures

Advances in convoy tactics, high-frequency direction finding (referred to as ("Huff-Duff"), radar, active
sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...
(called ASDIC in Britain), depth charges, ASW spigot mortars (also known as "hedgehog"), the intermittent cracking of the German Naval Enigma code, the introduction of the Leigh light, the range of escort aircraft (especially with the use of escort carriers), the use of mystery ships, and the full entry of the U.S. into the war with its enormous shipbuilding capacity, all turned the tide against the U-boats. In the end, the U-boat fleet suffered extremely heavy casualties, losing 793 U-boats and about 28,000 submariners (a 75% casualty rate, the highest of all German forces during the war). At the same time, the Allies targeted the U-boat shipyards and their bases with strategic bombing.


Enigma machine

The British had a major advantage in their ability to read some German naval Enigma codes. An understanding of the German coding methods had been brought to Britain via France from Polish code-breakers. Thereafter, code books and equipment were captured by raids on German weather ships and from captured U-boats. A team including
Alan Turing Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical ...
used special purpose " Bombes" and early
computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These prog ...
s to break new German codes as they were introduced. The speedy decoding of messages was vital in directing convoys away from wolf packs and allowing interception and destruction of U-boats. This was demonstrated when the Naval Enigma machines were altered in February 1942 and wolf-pack effectiveness greatly increased until the new code was broken. The , a Type IXB, was captured in 1941 by the
Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against Fr ...
, and its Enigma machine and documents were removed. was also captured by the British in October 1942; three sailors boarded her as she was sinking, and desperately threw all the code books out of the submarine so as to salvage them. Two of them, Able Seaman
Colin Grazier Colin Grazier, GC (7 May 1920 – 30 October 1942) was a sailor in the Royal Navy who was posthumously awarded the George Cross for the "outstanding bravery and steadfast devotion to duty in the face of danger" which he displayed on 30 October 1 ...
and Lieutenant
Francis Anthony Blair Fasson Lieutenant Francis Anthony Blair Fasson, (17 July 1913 – 30 October 1942), known as Tony Fasson, was a Royal Navy officer. He was posthumously awarded the George Cross "for outstanding bravery and steadfast devotion to duty in the face of da ...
, continued to throw code books out of the ship as it went under water, and went down with it. Further code books were captured by raids on weather ships. was boarded by crew from the Canadian ship on 6 March 1944, and codes were taken from her, but by this time in the war, most of the information was known. The , a Type IXC, was captured by the
United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
in June 1944. It is now a museum ship in Chicago at the Museum of Science and Industry. U-570 a Type VIIC was captured by the British in mid-1941. Although the crew managed to destroy their Enigma machine the British captured a quantity of papers which proved extremely useful to the cryptanalysts at
Bletchley Park Bletchley Park is an English country house and estate in Bletchley, Milton Keynes (Buckinghamshire) that became the principal centre of Allied code-breaking during the Second World War. The mansion was constructed during the years following ...
. The Royal Navy were able to tow the sinking submarine to Iceland where it was salvaged and later commissioned into the Royal Navy as HMS Graph carrying out 3 war patrols before being relegated to training duties. Mock-ups of the submarine interior were created to train specialist Royal Navy boarding parties in the event a U-boat was blown to the surface to reverse any scuttling attempts by the crew, and to search quickly for cryptographic equipment and documents.


Battle of Bell Island

Two events in the battle took place in 1942 when German U-boats attacked four allied ore carriers at Bell Island,
Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...
. The carriers and were sunk by on 5 September 1942, while the and ''PLM 27'' were sunk by on 2 November with the loss of 69 lives. When the submarine launched a torpedo at the loading pier, Bell Island became the only location in North America to be subject to direct attack by German forces in World War II.


Operation Deadlight

"Operation Deadlight" was the code name for the scuttling of U-boats surrendered to the Allies after the defeat of Germany near the end of the war. 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.


Memorial


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

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 submarine A coastal submarine or littoral submarine is a small, maneuverable submarine with shallow draft well suited to navigation of coastal channels and harbors. Although size is not precisely defined, coastal submarines are larger than midget submarine ...
s to protect against the
Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
threat in the
Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from ...
. The Germans sought to use advanced technologies to offset the small displacement, such as amagnetic
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...
to protect against
naval mine A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an ...
s and
magnetic anomaly detector A magnetic anomaly detector (MAD) is an instrument used to detect minute variations in the Earth's magnetic field. The term refers specifically to magnetometers used by military forces to detect submarines (a mass of ferromagnetic material c ...
s. The initial Type 201 was a failure because of hull cracking; the subsequent Type 205, first commissioned in 1967, was a success, and 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 The Israeli Navy ( he, חיל הים הישראלי, ''Ḥeil HaYam HaYisraeli'' (English: The Israeli Sea Corps); ar, البحرية الإسرائيلية) is the naval warfare service arm of the Israel Defense Forces, operating primarily in ...
, 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 would continue 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 Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...
. Germany would continue to succeed as an exporter of submarines as the Klasse 210 sold to
Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of ...
, considered the most silent and maneuverable submarines in the world. This would demonstrate its capacity and put its export seal on the world. Germany has brought the U-boat name into the 21st century with the new
Type 212 The German Type 212 class (German: U-Boot-Klasse 212 A), also Italian ''Todaro'' class, is a diesel-electric submarine developed by Howaldtswerke-Deutsche Werft AG (HDW) for the German and Italian navies. It features diesel propulsion and an ...
. The 212 features an air-independent propulsion system using
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
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 and Norway, the Type 214 has been designed as the follow-on export model and has been sold to
Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders wi ...
,
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
,
Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolian Peninsula in Western Asia, with a small portion on the Balkan Peninsula ...
, and based on it would get the Type U 209PN sold to
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of th ...
. In recent years Germany introduced new models such as the Type 216 and the Type 218 the latter being sold to
Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, bor ...
. In 2016, Germany commissioned its newest U-boat, the ''U-36'', a Type 212.


See also

* List of U-boats of Germany * List of U-boats never deployed * List of successful U-boats * '' Das Boot'', 1981 German U-boat film * '' Greyhound'', 2020 American war film *
Decoy A decoy (derived from the Dutch ''de'' ''kooi'', literally "the cage" or possibly ''ende kooi'', " duck cage") is usually a person, device, or event which resembles what an individual or a group might be looking for, but it is only meant to lu ...
s **
Bold (decoy) Bold (a term derived from kobold) was a German sonar decoy, used by U-boats during the Second World War from 1942 onwards. It consisted of a metal canister about in diameter filled with calcium hydride. It was launched by an ejector system coll ...
**
Sieglinde (decoy) Sieglinde was a sonar decoy used during the Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's count ...
* Karl Dönitz * List of Knight's Cross recipients of the U-boat service *
Orkney Wireless Museum The Orkney Wireless Museum in Kirkwall, Orkney, Scotland, houses a collection of domestic and military wireless equipment. It developed from the private collection of the late Jim MacDonald from St Margaret's Hope and marks the importance of wire ...
contains an example of a U-boat radio *
I-boat Imperial Japanese Navy submarines originated with the purchase of five Holland type submarines from the United States in 1904. Japanese submarine forces progressively built up strength and expertise, becoming by the beginning of World War II one ...
, Japanese equivalent


References


Further reading

*Abbatiello, John (2005) ''Anti-Submarine Warfare in World War I: British Naval Aviation and the Defeat of the U-Boats'' *Buchheim, Lothar-Günther. ''Das Boot'' (original German edition 1973, eventually translated into English and many other Western languages).
Movie adaptation A film adaptation is the transfer of a work or story, in whole or in part, to a feature film. Although often considered a type of derivative work, film adaptation has been conceptualized recently by academic scholars such as Robert Stam as a dial ...
in 1981, directed by Wolfgang Petersen *Gannon, Michael (1998) ''Black May''. Dell Publishing. *Gannon, Michael (1990) ''Operation Drumbeat''. Naval Institute Press. *Gray, Edwyn A. (1994) ''The U-Boat War, 1914–1918'' *Hans Joachim Koerver (2010) ''German Submarine Warfare 1914–1918 in the Eyes of British Intelligence'', LIS Reinisch, *Kurson, Robert (2004) ''Shadow Divers: The True Adventure of Two Americans Who Risked Everything to Solve One of the Last Mysteries of World War II''. Random House Publishing. *Möller, Eberhard and Werner Brack (2006) ''The Encyclopedia of U-Boats: From 1904 to the Present'', * O'Connor, Jerome M. (June 2000) "Inside the Grey Wolves' Den." ''Naval History''. The US Naval Institute Author of the Year feature describes the building and operation of the German U-boat bases in France. *Preston, Anthony (2005) ''The World's Greatest Submarines''. *Stern, Robert C. (1999) ''Battle Beneath the Waves: U-boats at war''. Arms and Armor/Sterling Publishing. . *Showell, Jak Mallmann (2006) ''The U-boat Century: German Submarine Warfare, 1906–2006'', *van der Vat, Dan (1988) ''The Atlantic Campaign''. Harper & Row. Connects submarine and antisubmarine operations between World War I and World War II, and suggests a continuous war. *Von Scheck, Karl. ''U122: The Diary of a U-boat Commander''. Diggory Press, *Georg von Trapp and Elizabeth M. Campbell (2007) ''To the Last Salute: Memories of an Austrian U-Boat Commander'' *Westwood, David (2005) ''U-Boat War: Doenitz and the evolution of the German Submarine Service 1935–1945'', *Werner, Herbert. '' Iron Coffins: A Personal Account of the German U-Boat Battles of World War II'',


External links


U-112 and U-53 Submarine Collection
at Dartmouth College Library {{DEFAULTSORT:U-Boat 01 Submarines of Germany Submarines of the Imperial German Navy Submarines of the Kriegsmarine German Empire in World War I Germany in World War II Submarines by type World War I submarines World War II submarines