Military Wiki
SM U-20 (Germany)
Postcard depicting U-20 sinking RMS Lusitania.
Career (German Empire)
Name: U-20
Ordered: 25 November 1910
Builder: Kaiserliche Werft Danzig
Cost: 2,450,000 Goldmark
Yard number: 14
Laid down: 7 November 1911
Launched: 18 December 1912
Commissioned: 5 August 1913
Fate: Grounded 4 November 1916 and destroyed by her crew the next day.
General characteristics
Class & type: German Type U 19 submarine
Displacement: 650 t (720 short tons) ↑
837 t (923 short tons) ↓
Length: 64.15 m (210 ft 6 in)
Beam: 6.1 m (20 ft 0 in)
Height: 7.30 m (23 ft 11 in)
Draught: 3.58 m (11 ft 9 in)
Propulsion: 2 shafts
2 × MAN 8-cylinder two stroke diesel motors with 1,700 PS (1,700 hp)
2 × AEG double Motordynamos with 1,200 PS (1,200 hp)
320 rpm ↓
Speed: 15.4 knots (28.5 km/h) ↑
9.5 knots (17.6 km/h) ↓
Range: 9,700 nautical miles (11,200 mi; 18,000 km) @ 8 kn ↑
80 nautical miles (92 mi; 150 km) @ 5 kn ↓
Test depth: 50 m (164 ft 1 in)
Boats & landing
craft carried:
1 dingi
Complement: 4 officers, 31 men
Armament: 4 x 50 cm (19.7 in) torpedo tubes (2 each bow and stern) with 6 torpedoes
1 × 8.8 cm (3.5 in) SK L/30 gun (from 1916 2 ×)
1 x 3.7 cm (1.5 in) Hotchkiss gun
Service record
Part of: Imperial German Navy:
III Flottille
Commanders: Otto Dröscher 1 Aug 1914 – 15 Dec 1914
Walther Schwieger 16 Dec 1914 – 5 Nov 1916[1]
Operations: 7
Victories: 36 ships sunk for a total of 144.300 tons, including RMS Lusitania.

SM U-20 was a German Type U 19 U-boat built for service in the Imperial German Navy. She was launched on 18 December 1912, and commissioned on 5 August 1913. During World War I, she took part in operations around the British Isles. The U-20 became infamous following her sinking of the British ocean liner RMS Lusitania on 7 May 1915, an act that dramatically reshaped the course of World War I.


On 7 May 1915, U-20 was patrolling off the southern coast of Ireland under the command of Kapitänleutnant Walther Schwieger. Three months earlier, on 4 February, the Germans had established a U-boat blockade around Great Britain and Ireland and had declared any vessel in it a legitimate target.

At about 1:40 pm Schwieger saw a vessel approaching through his periscope. From a distance of about 700 m Schwieger noted she had four funnels and two masts making her a liner of some sort. He recognised her as the Lusitania, a vessel in the British Fleet Reserve, and fired a single torpedo. It hit on the starboard side, almost directly below the bridge. Following the torpedo's explosion, the liner was shattered by a second explosion, possibly caused by either coal dust, munitions in the hold, or a boiler explosion, so large Schwieger himself was surprised. In 18 minutes, Lusitania had sunk to the bottom, where she lies today in 300 feet of water, with 1198 casualties.

Fifteen minutes after he had fired his torpedo, Schwieger noted in his war diary:

"It looks as if the ship will stay afloat only for a very short time. [I gave order to] dive to 25 metres and leave the area seawards. I couldn't have fired another torpedo into this mass of humans desperately trying to save themselves."

There was at the time and remains now a great controversy about the sinking, over whether Lusitania was smuggling contraband war material to England and over the number of torpedoes Schwieger fired.

Before he got back to the docks at Wilhelmshaven for refuelling and resupply, the United States had formally protested to Berlin against the brutality of his action.

Kaiser Wilhelm II wrote in the margins of the American note, "Utterly impertinent", "outrageous", and "this is the most insolent thing in tone and bearing that I have had to read since the Japanese note last August." Nevertheless, to keep America out of the war, in June the Kaiser was compelled to rescind unrestricted submarine warfare and require all passenger liners be left unmolested.

U-20 and her fleetmates in Kiel harbour, 1914

On 4 September 1915 Schwieger was back at sea with U-20, eighty-five miles[Clarification needed] off the Fastnet Rock in the south Irish Sea. This rock held one of the key navigational markers in the western ocean, the Fastnet Lighthouse, and any ships passing in and out of the Irish Sea would be within visual contact of it.

RMS Hesperian was now beginning a new run outward bound from Liverpool to Quebec and Montreal, with a general cargo, also doubling as a hospital ship, and carrying about 800 passengers. She was attacked off the Fastnet, a landmark islet in the north Atlantic, off the south-west coast of Ireland. The "History of the Great War: The Merchant Navy, Vol. II", by Hurd, reads:

"Only a few days before, Count Bernsdorff, the German Ambassador, had assured the United States government that passenger liners will not be sunk without warning and without ensuring the safety of the non combatants aboard providing that the liners do not try to escape or offer resistance."

This time, Schwieger was received with official disgust upon his return to Wilhelmshaven. Ordered to report to Berlin to explain himself, he was required to apologise for having sunk another passenger liner in defiance of a direct order not to do so again. He complained about his treatment in Berlin thereafter.

After his death in 1917, Schwieger was forgiven in Berlin. He received Germany's highest decoration, the Pour le Mérite, having sunk by that time 190,000 tons of ships.


U-20 grounded on the Danish coast in 1916. Torpedoes had been exploded in the bow to destroy the ship

On 4 November 1916 U-20 grounded on the Danish coast around position 56°33′N 08°08′E / 56.55°N 8.133°E / 56.55; 8.133 at Vrist, a little north of Thorsminde after suffering damage to its engines. Her crew destroyed her in an explosion the following day.[2]

Post scripts


After the explosion, the Danish navy removed the deck gun and made it unserviceable by cutting holes in vital parts. The gun was kept in the naval stores at Holmen in Copenhagen for almost 80 years.

Conning tower

The conning tower of U-20 has been recovered. It is now on display at the Strandingsmuseum St. George Thorsminde.


Novelist Clive Cussler claims his National Underwater and Marine Agency (NUMA) located the remains of U-20 in 1984.[3]

Original documents from Room 40

The following is a verbatim transcription of the recorded activities of SM U-20 known to British Naval Intelligence, Room 40 O.B.:[4]

"SM U-20.

Kaptlt. Dröscher, October 1914, later to U-78; Kaptlt. Schwieger in April 1915, later to U-88. Completed at Danzig before the war and subsequently joined the 3rd Half Flotilla.

  • September 1914. Cruising.
  • October 1914. Cruising.
  • 25th – 26 December 1914. Patrolling in Bight.
  • 26 January – 7 February 1915. Cruise to Channel. Sank 3 S.S.
  • 25 February – 19 March 1915. Cruise to Bristol Channel putting into Zeebrugge on outward and into Ostend on homeward passage. Sank 1 S.S.
  • 30 April – 13 May 1915. Northabout to south of Ireland. Sank RMS LUSITANIA, 2 other S.S., and 1 sailing vessel.
  • 3–16 July 1915. Northabout to south of Ireland. Sank 4 S.S., 1 sailing vessel.
  • 29 August – 15 September 1915. Northabout of Bay of Biscay. 9 S.S. and 2 sailing vessels sunk.
  • 17–23 November 1915. North Sea, apparently some special task.
  • 17–23 December 1915 ? Bight patrol.
  • 7–10 April 1916. North Sea, ordered 8 April to return.
  • 11–15 April 1916. North Sea, returned with defective torpedo tubes.
  • 24 April to 14 May 1916. Northabout to south of Ireland. Sank 2 S.S., 3 sailing vessels.
  • 16 June to 20 June 1916. Bight patrol.
  • ? 3 July to 13 July 1916. North Sea patrol.
  • 21 to 24 July 1916. North Sea patrol.
  • 26 July to 2 August 1916. North Sea patrol.
  • 21 September to 28 September 1916. North Sea patrol. Sank 1 steamer ship.
  • 13 October to 5 November 1916. Northabout to south of Ireland. Sank 3 S.S., 1 sailing vessel. Ran ashore on Danish coast 5 November 1916 and was blown up by crew."

Note: S.S. = Steam Ship; S.V. = Sailing Vessel; northabout, Muckle Flugga, Fair I. = around Scotland; Sound, Belts, Kattegat = via North of Denmark to/from German Baltic ports; Bight = to/from German North Sea ports; success = sinking of ships

See also


  2. "Major themes of the exhibition", 'World War I'. Royal Danish Naval Museum (Archived from the original on 8 October 2007)
  3. North Sea and English Channel Hunt
  4. National Archives, Kew: HW 7/3, Room 40, History of German Naval Warfare 1914–1918 (Published in Koerver, 'Room 40: German Naval Warfare 1914–1918')


  • Spindler, Arno (1932,1933,1934,1941/1964,1966). Der Handelskrieg mit U-Booten. 5 Vols. Berlin: Mittler & Sohn. Vols. 4+5, dealing with 1917+18, are very hard to find: Guildhall Library, London, has them all, also Vol. 1–3 in an English translation: The submarine war against commerce. 
  • Beesly, Patrick (1982). Room 40: British Naval Intelligence 1914–1918. London: H Hamilton. ISBN 978-0241108642. 
  • Halpern, Paul G. (1920). A Naval History of World War I. New York: Routledge. ISBN 978-1857284980. 
  • Roessler, Eberhard (1997). Die Unterseeboote der Kaiserlichen Marine. Bonn: Bernard & Graefe. ISBN 978-3763759637. 
  • Schroeder, Joachim (2002). Die U-Boote des Kaisers. Bonn: Bernard & Graefe. ISBN 978-3763762354. 
  • Koerver, Hans Joachim (2008). Room 40: German Naval Warfare 1914–1918. Vol I., The Fleet in Action. Steinbach: LIS Reinisch. ISBN 978-3-902433-76-3. 
  • Koerver, Hans Joachim (2009). Room 40: German Naval Warfare 1914–1918. Vol II., The Fleet in Being. Steinbach: LIS Reinisch. ISBN 978-3-902433-77-0. 

External links

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