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Title: U-boat  
Author: World Heritage Encyclopedia
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Subject: 1942, List of submarines of the United States Navy, Glossary of German military terms, List of shipwrecks of Africa, 1915
Publisher: World Heritage Encyclopedia


U-Boat, by Augusto Ferrer-Dalmau.
U-995, a typical U-boat

U-boat is the anglicised version of the German word U-Boot  ( ), a shortening of Unterseeboot, which means "undersea boat".[1] While the German term refers to any submarine, the English one (in common with several other languages) refers specifically to military 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), 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, the British Empire, and the United States to the islands of the United Kingdom and (during the Second World War) to the Soviet Union and the Allied territories in the Mediterranean. Austro-Hungarian submarines of the First World War (and before it) were also known as U-boats.


The first submarine built in Germany was the three-man submarine Brandtaucher, which sank to the bottom of Kiel harbor during its first test dive.[2] The vessel was designed in 1850 by the inventor and engineer Wilhelm Bauer and built by Schweffel & Howaldt in Kiel for the Imperial German Navy. Brandtaucher was later rediscovered during dredging operations in 1887, and subsequently raised sixteen years later and placed in a museum in Germany, where it remains today.

This was followed in 1890 by WW1 and WW2, built to a Nordenfelt design. In 1903, Germaniawerft dockyard in Kiel completed Germany's first fully functional submarine, Forelle[3] which was sold to Russia during the Russo-Japanese War in April 1904.[4] The SM U-1 was a completely redesigned Karp-class submarine and only one was built. It was commissioned by the Imperial German Navy on 14 December 1906.[5] It had a double hull, was powered by a Körting kerosene engine and was armed with a single torpedo tube. The fifty percent larger SM U-2 had two torpedo tubes. A diesel engine was not installed in a German navy boat until the U-19 class of 1912–13. At the start of World War I, Germany had 48 submarines of 13 classes in service or under construction. During the First World War the SM U-1 was used for training and was retired in 1919. It is currently on display at the Deutsches Museum in Munich.[6]

World War I

German submarine U-9 (1910).

At the start of World War I, Germany had twenty-nine U-boats; in the first ten weeks, they sank five British cruisers. On 5 September 1914, 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 obsolete British warships HMS Aboukir, HMS Cressy and HMS Hogue (the "Live Bait Squadron") in a single hour.


For the first few months of the war, U-boat anti-commerce actions observed the "prize rules" of the time which governed the treatment of enemy civilian ships and their occupants. On 20 October 1914, SM U-17 sank the first merchant ship, the SS Glitra, off Norway.[8] Surface commerce raiders were proving to be ineffective, and on 4 February 1915, the Kaiser 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 was rammed and sunk off Beachy Head by the collier SS Thordis commanded by Captain John Bell RNR after firing a torpedo.[9] On 7 May 1915, SM U-20 sank the liner RMS Lusitania. The sinking claimed 1,198 lives, 128 of them American civilians, and deeply shocked the Allies because an unarmed civilian passenger ship was attacked. According to the ship's manifest, Lusitania was carrying military cargo, though none of them were classified as ammunition since they were classed as small arms and had bulk of non-explosives. This widely made the ship a non-military target. In fact, Lusitania had been carrying small arms for years prior to the sinking in 1915. It was not until the sinking of the ferry SS Sussex that there was a widespread reaction in the USA.

The initial U.S. response was to threaten to sever diplomatic ties, which persuaded the Germans to issue the Sussex pledge that re-imposed restrictions on U-boat activity. The U.S. reiterated its objections to German submarine warfare whenever U.S. civilians died as a result of German attacks, which prompted the Germans to fully re-apply prize rules. This, however, removed the effectiveness of the U-boat fleet, and the Germans consequently sought a decisive surface action, a strategy which 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 anti-commerce 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.



Unrestricted submarine warfare in the spring of 1917 was initially very successful, sinking a major part of Britain-bound shipping. Nevertheless 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 and all surviving German submarines were surrendered. Of the 360 submarines that had been built, 178 were lost but more than 11 million tons of shipping had been destroyed.


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, scrapped, or given to Allied navies. Stephen King-Hall wrote a detailed eyewitness account of the surrender.[10]



World War II


In the early stages of the war, the U-boats were extremely effective in destroying Allied shipping, initially in the mid-Atlantic up until 1942 when the tides changed, where there was a large gap in air cover. There was an extensive trade in war supplies and food across the Atlantic, which was critical for Britain's survival. This continuous action became known as the Battle of the Atlantic, as the British developed technical defences such as ASDIC and radar, 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. Later, when the United States entered the war, the U-boats ranged from the Atlantic coast of the United States and Canada to the Gulf of Mexico, and from the Arctic 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, in order 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 which had the ability to 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. Indeed, while U-boats were faster on the surface than submerged, the opposite is generally true of modern subs. The most common U-boat attack during the early years of the war was conducted on the surface and at night, see submarine warfare. This period, before the Allied forces developed truly effective antisubmarine warfare (ASW) tactics, which included convoys, was referred to by German submariners as "die glückliche Zeit" or "the happy time."[13]

U-534, Birkenhead Docks, Merseyside, England



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 meters and then turn toward the loudest noise detected. This sometimes ended up being the U-boat itself; at least two submarines may have been sunk by their own homing torpedoes. Additionally, it was found these torpedoes were only effective against ships moving at greater than 15 knots (28 km/h). At any rate, the Allies countered acoustic torpedoes with noisemaker decoys such as Foxer, 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 torpedo. However, the T11 torpedoes did not see active service.[16]

U-boats also adopted several types of "pattern-running" torpedoes which 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 are Type VII, known as the "workhorse" of the fleet, which was by far the most-produced type and the Type IX boats which were larger versions of the VII but specifically 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 air-independent propellant system. These boats featured a streamlined hull design, which formed the basis of the later USS Nautilus 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.

Throughout the war an arms race evolved between the Allies and the Kriegsmarine, especially in detection and counter-detection. Sonar (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 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 AA guns. However, by early/mid 1943 the Allies switched to centimetric radar (unbeknownst 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.

The Germans experimented with the idea of the Schnorchel (snorkel) from captured Dutch submarines, early on but didn't see the need for them until rather late in the war. The Schnorchel was a retractable pipe which 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. There were problems 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. Waste disposal, as is today, was a problem when the U-boats spent extended periods without surfacing. Speed was limited to 8 knots (15 km/h), 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 itself 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.






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 used special purpose "Bombes" and early computers 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 German submarine U-110, a Type IXB, was captured in 1941 by the Royal Navy, and its Enigma machine and documents were removed. U-559 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. Two of them, Able Seaman Colin Grazier and Lieutenant Francis Anthony Blair Fasson 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. U-744 was boarded by crew from the Canadian ship HMCS Chilliwack on 6 March 1944, and codes were taken from her, but by this time in the war most of the information was known.[17] The U-505, a Type IXC, was captured by the United States Navy in June 1944. It is presently a museum ship in Chicago at the Museum of Science and Industry.

Battle of Bell Island


Operation Deadlight


Post World War II




With the Danish government's purchase of two Type 205 boats, the German government realized the potential for the submarine as an export. Three of the improved Type 206 boats were sold to the Israeli Navy becoming the Gal-class. 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.



See also



  1. ^ "U-boat". Online Etymolgy Dictionary. Retrieved 2012-06-22. 
  2. ^ Showell, p. 23
  3. ^ Showell, p. 201
  4. ^ Showell, p.22, 23, 25, 29
  5. ^ Showell, p. 30
  6. ^ Showell, p. 36 & 37
  7. ^
  8. ^ "WWI U-Boats U-17". Retrieved 2008-03-24. 
  9. ^ Haley Dixon (21 June 2013). "Story of Captain’s courage resurfaces after 98 years". Daily Telegraph. Retrieved 22 June 2013. 
  10. ^ A North Sea diary, 1914-1918, Chapter XIX
  11. ^ For other warships, Germany was permitted lesser amounts compared to the UK
  13. ^ Military History Online
  16. ^ The Torpedoes - Technical pages - German U-boats of WWII - Kriegsmarine -
  17. ^ Helgason, Gudmundur "Captured U Boats" UBoat.Net

Further reading

  • Buchheim, Lothar-Günther, Das Boot (Original German edition 1973, eventually translated into English and many other Western languages). Movie adaptation in 1981, directed by Wolfgang Petersen
  • O'Connor, Jerome M. "Inside the Grey Wolves Den." Naval History, June 2000. The US Naval Institute Author of the Year feature describes the building and operation of the German U-boat bases in France.
  • van der Vat, Dan. The Atlantic Campaign Harper & Row, 1988. 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 ISBN 978-1-84685-049-3

External links

  • TheSubPen The Sub "Pen." Your Home for Submarine and U-boat History. Good for research, curiosity and fun.
  • Comprehensive reference source for WW I and WW II U-boat information.
  • The German U-boat bases of the WW-II in France : Brest, Lorient, St-Nazaire, La Rochelle, Bordeaux.
  • Comprehensive reference source for WW II U-boat information.
  • [1] US Naval Institute award winning INSIDE THE U-BOAT PENS, describing the construction and operation of the five U-boat bases along the Bay of Biscay in France. Photos, diagrams, including visit to Admoral Donitz unknown command and control chateau in Lorient, France.

