SM U-20 (Germany)

SM U-20[Note 1] 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. 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.

Postcard depicting U-20 sinking RMS Lusitania.
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 and type: German Type U 19 submarine
  • 650 t (640 long tons) surfaced
  • 837 t (824 long tons) submerged
Length: 64.15 m (210 ft 6 in)
Beam: 6.10 m (20 ft)
Height: 7.30 m (23 ft 11 in)
Draught: 3.58 m (11 ft 9 in)
  • 2 shafts
  • 2 × MAN 8-cylinder two stroke diesel motors with 1,700 PS (1,250 kW; 1,680 shp)
  • 2 × AEG double Motordynamos with 1,200 PS (880 kW; 1,180 shp)
  • 320 rpm submerged
  • 15.4 knots (28.5 km/h; 17.7 mph) surfaced
  • 9.5 knots (17.6 km/h; 10.9 mph) submerged
  • 9,700 nautical miles (18,000 km; 11,200 mi) at 8 kn surfaced
  • 80 nautical miles (150 km; 92 mi) at 5 kn submerged
Test depth: 50 m (164 ft 1 in)
Boats & landing
craft carried:
1 dinghy
Complement: 4 officers, 31 men
Service record
Part of:
Operations: 7 patrols
Victories: 36 merchant ships sunk (144,300 GRT), including RMS Lusitania.


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 the British Isles and had declared any vessel in it a legitimate target.

At about 13:40 Schwieger was at the periscope and saw a vessel approaching. From a distance of about 700 metres (770 yd) 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 coal dust, a boiler explosion, or a explosion in the propulsion system – so large Schwieger himself was surprised. In 18 minutes, Lusitania sank with 1,198 casualties. The wreck lies in 300 feet (91 m) of water.

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 (82 ft) 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 a great controversy about the sinking, over whether Lusitania was smuggling contraband war material to England and over the number of torpedoes Schwieger fired. The Allies and the United State originally thought the U-20 fired two torpedoes. Postwar investigations showed only one was 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.

On 4 September 1915 Schwieger was back at sea with U-20, 85 nautical miles (157 km; 98 mi) 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 190,000 tons of shipping.

Fate and legacy

On 4 November 1916, U-20 grounded on the Danish coast south of Vrist, a little north of Thorsminde after suffering damage to its engines. Her crew attempted to destroy her with explosives the following day, succeeding, however, only in damaging the boat's bow (see picture) but making it effectively inoperative as a war ship.[4] The boat remained on the beach until 1925 when the Danish government blew it up in a "spectacular explosion".[5] 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. The conning tower was removed and placed on the front lawn of the local museum Strandingsmuseum St. George Thorsminde, where it still is today.[5][6][7]

Novelist Clive Cussler claims his National Underwater and Marine Agency (NUMA) located the remains of U-20 in 1984, about 400 yards from shore.[8]

Summary of raiding history

Date Name Nationality Tonnage[Note 2] Fate[9]
30 January 1915 Ikaria  United Kingdom 4,335 Sunk
30 January 1915 Oriole  United Kingdom 1,489 Sunk
30 January 1915 Tokomaru  United Kingdom 6,084 Sunk
7 March 1915 Bengrove  United Kingdom 3,840 Sunk
9 March 1915 Princess Victoria  United Kingdom 1,108 Sunk
11 March 1915 Florazan  United Kingdom 4,658 Sunk
5 May 1915 Earl of Lathom  United Kingdom 132 Sunk
6 May 1915 Candidate  United Kingdom 5,858 Sunk
6 May 1915 Centurion  United Kingdom 5,495 Sunk
7 May 1915 Lusitania  United Kingdom 30,396 Sunk
8 July 1915 Marion Lightbody  Russian Empire 2,176 Sunk
9 July 1915 Ellesmere  United Kingdom 1,170 Sunk
9 July 1915 Leo  Russian Empire 2,224 Sunk
9 July 1915 Meadowfield  United Kingdom 2,750 Sunk
13 July 1915 Lennok  Russian Empire 1,142 Sunk
2 September 1915 Roumanie  United Kingdom 2,599 Sunk
3 September 1915 Frode  Denmark 1,875 Sunk
4 September 1915 Hesperian  United Kingdom 10,920 Sunk
5 September 1915 Dictator  United Kingdom 4,116 Sunk
5 September 1915 Douro  United Kingdom 1,604 Sunk
5 September 1915 Rhea  Russian Empire 1,145 Sunk
6 September 1915 Guatemala  France 5,913 Sunk
7 September 1915 Bordeaux  France 4,604 Sunk
7 September 1915 Caroni  United Kingdom 2,652 Sunk
8 September 1915 Mora  United Kingdom 3,047 Sunk
30 April 1916 Bakio  Spain 1,906 Sunk
1 May 1916 Bernadette  France 486 Sunk
2 May 1916 Ruabon  United Kingdom 2,004 Sunk
3 May 1916 Marie Molinos  France 1,946 Sunk
6 May 1916 Galgate  United Kingdom 2,356 Sunk
8 May 1916 Cymric  United Kingdom 13,370 Sunk
1 August 1916 Aaro  United Kingdom 2,603 Sunk
29 August 1916 Ibo  Portugal 397 Damaged
26 September 1916 Thelma  United Kingdom 1,002 Sunk
18 October 1916 Ethel Duncan  United Kingdom 2,510 Sunk
23 October 1916 Arromanches  France 1,640 Sunk
23 October 1916 Chieri  Kingdom of Italy 4,400 Sunk
23 October 1916 Felix Louis  France 275 Sunk
26 October 1916 Fabian  United Kingdom 2,246 Damaged

See also



  1. "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.
  2. Tonnages are in gross register tons


  1. Helgason, Guðmundur. "WWI U-boat commanders: Otto Dröscher (Royal House Order of Hohenzollern)". German and Austrian U-boats of World War I - Kaiserliche Marine - Retrieved 15 March 2015.
  2. Helgason, Guðmundur. "WWI U-boat commanders: Walther Schwieger (Pour le Mérite)". German and Austrian U-boats of World War I - Kaiserliche Marine - Retrieved 15 March 2015.
  3. Helgason, Guðmundur. "WWI U-boats: U 20". German and Austrian U-boats of World War I - Kaiserliche Marine - Retrieved 14 March 2015.
  4. "Major themes of the exhibition", 'World War I'. Royal Danish Naval Museum (Archived from the original on 8 October 2007)
  5. Erik Larson (2015). "Epilogue: Person Effects". Dead Wake: The Last Crossing of the Lusitania. Crown. p. 349.
  6. "Strandingsmuseum St. George Thorsminde". Archived from the original on 29 October 2013. Retrieved 15 March 2015.
  7. "Sea War Museum Jutland".
  8. North Sea and English Channel Hunt Archived 28 December 2003 at the Wayback Machine
  9. Helgason, Guðmundur. "Ships hit by U 20". German and Austrian U-boats of World War I - Kaiserliche Marine - Retrieved 14 December 2014.


  • Gröner, Erich; Jung, Dieter; Maass, Martin (1991). U-boats and Mine Warfare Vessels. German Warships 1815–1945. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.
  • Spindler, Arno (1966) [1932]. 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.

<ref>specs for U20 listed in the U.boat Archive web site

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