Military Wiki
SM U-108
Career (German Empire)
Name: U-108
Builder: Germaniawerft, Kiel
Yard number: Werk 277
Laid down: 5 May 1916
Launched: 11 October 1917
Commissioned: 5 December 1917
Renamed: Léon Mignot
Struck: 24 July 1935
General characteristics
Class & type: German Type U 93 submarine
Displacement: 808 tons (surfaced)
946 tons (submerged)
1160 tons (total)
Length: 70.60 m (overall)
55.55 m (pressure hull)
Beam: 6.30 m (overall)
4.15 m (pressure hull)
Draught: 4.02 m
Propulsion: 2400 hp (surfaced)
1200 hp (submerged)
Speed: 16.8 knots (surfaced)
9.1 knots (submerged)
Range: 11,220 miles (surfaced) 56 miles (submerged)
Complement: 39 men
Armament: 16 torpedoes (4/2 in bow/stern tubes)
105mm deck gun with 220 rounds
88mm deck gun

SM U-108 was one of 329 submarines serving in the Imperial German Navy in World War I. U-108 was engaged in commerce warfare in the First Battle of the Atlantic. Launched in 1917, she survived the war, being surrendered in 1918 and becoming the French submarine Léon Mignot.[1]


U-108 came off the stocks of the Weser yard in Bremen in late 1917 or early 1918, and was commanded by Korvettenkapitän (Lieutenant commander) Martin Nitzsche.[2] She trained her crew at the Kiel school between 24 January and 26 March 1918, and was attached to Fourth Flotilla; all her operational activities took place in 1918. She was first detected by Room 40 (which followed and recorded all her subsequent movements) in the North Sea, on 14 April.[3]

On 21 April, she departed on her first war patrol, to the English Channel, which lasted until the patrol was terminated 6 May due to a serious oil leak, as well as other damage.[4] the product of depth charge attack by the U.S. A/S destroyer, Porter[5] on 28 April.[6]

Following refit, her second patrol commenced 6 July, when she departed for the southwest coast of Ireland and the Western Approaches. She sank one steamer (not identified by Room 40) on 15 July, and may have made an unsuccessful attack on a convoy two days later.[7] On 30 July, SM U-60 warned her of a possible enemy submarine in the Skagerrak. She returned home successfully 1 August.

U-108's third patrol began 8 October, but was cut short 15 October due to reported defects.[8] (These would have been in a message intercepted and decrypted by Room 40.) After repairs, she sortied again 19 October into the North Sea. In her patrol area, she reported depth charge attacks by airships and aircraft, as well as contact with enemy submarines.[9] She was detailed to an advanced station on 28 October to await an attack on enemy battleships, which Room 40 believed was in connection with a sortie by the High Seas Fleet[10] (whose actions Room 40 was also monitoring).[11] Nothing materialized, and she returned to port with her W/T (wireless telegraph) out of commission.[12]

U-108 surrendered 20 November 1918 at Harwich.


  1. "U-108". Retrieved 25 January 2010. 
  2. Koerver, Hans Joachim. Room 40: German Naval Warfare 1914-1918. Vol II., The Fleet in Being (Steinbach, Germany: LIS Reinisch, 2009).
  3. Koerver.
  4. Koerver.
  5. Koerver. Room 40 describes her as a "TBD", or torpedo boat destroyer, an older term.
  6. Koerver.
  7. Koerver.
  8. Koerver.
  9. Koerver.
  10. Koerver.
  11. Beesley, Patrick. Room 40.
  12. Koerver.


  • 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 978-0-241-10864-2. 
  • Halpern, Paul G. (1995). A Naval History of World War I. New York: Routledge. ISBN 978-1-85728-498-0. 
  • Roessler, Eberhard (1997). Die Unterseeboote der Kaiserlichen Marine. Bonn: Bernard & Graefe. ISBN 978-3-7637-5963-7. 
  • Schroeder, Joachim (2002). Die U-Boote des Kaisers. Bonn: Bernard & Graefe. ISBN 978-3-7637-6235-4. 
  • 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. 

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