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	The design for U-23 was based on that of the Havmanden class of the Royal Danish Navy (Havmanden pictured)
History
Austria-Hungary
Name	SM U-23
Ordered	27 March 1915
Builder	Hungarian UBAG yard, Fiume
Launched	5 January 1917
Commissioned	1917
Fate	Sunk by Italian destroyer Airone, 21 February 1918
Service record
Commanders:	Klemens Ritter von Bézard; 15 April 1917 - 21 February 1918;
Victories:	None
General characteristics
Type	U-20-class submarine
Displacement	173 t, surfaced; 210 t, submerged;
Length	127 ft 2 in (38.76 m)
Beam	13 ft (4.0 m)
Draft	9 ft (2.7 m)
Propulsion	1 × shaft; 1 × diesel engine, 450 bhp (340 kW); 1 × electric motor, 160 shp (120 kW);
Speed	12 knots (22 km/h) surfaced; 9 knots (17 km/h) submerged;
Range	1,400 nautical miles (2,600 km) at 10 knots (19 km/h) surfaced; 23 nautical miles (43 km) at 8 knots (15 km/h) submerged;
Complement	18
Armament	2 × 45 cm (17.7 in) torpedo tubes (both in front); 2 torpedoes; 1 × 66 mm (2.6 in)/26 deck gun; 1 × 8 mm (0.31 in) machine gun;

SM U-23 or U-XXIII was a U-20-class submarine or U-boat built for and operated by the Austro-Hungarian Navy (German: Kaiserliche und Königliche Kriegsmarine or K.u.K. Kriegsmarine) during the First World War. The design for U-23 was based on that of the submarines of the Royal Danish Navy's Havmanden class (which had been designed by Whitehead & Co. in Fiume), and was largely obsolete by the beginning of the war.

U-23 was just over 127 feet (39 m) long and was armed with two bow torpedo tubes, a deck gun, and a machine gun. In February 1918, U-23 was sunk with all hands by the Italian torpedo boat Airone while attempting an attack on the Italian transport Memfi. U-23 had no wartime successes.

Design and construction

When it became apparent to the Austro-Hungarian Navy that the First World War would not be a short one,^[1] they moved to bolster their U-boat fleet by seizing the plans for the Danish Havmanden class submarines,^[2] which had been designed by Whitehead & Co. in Fiume, who had built three units.^[6] Although the Austro-Hungarian Navy was not happy with the design, which was largely obsolete,^[4]^[7] it was the only design for which plans were available and which could be begun immediately in domestic shipyards.^[7] The Austro-Hungarian Navy unenthusiastically placed orders for U-23 and her three sister boats on 27 March 1915.^[1]

U-23 was one of two boats of the class to be built at the Hungarian UBAG yard in Fiume.^[2] Due to demands by the Hungarian government,^[1] subcontracts for the class were divided between Hungarian and Austrian firms,^[3] and this politically expedient solution worsened technical problems with the design, resulting in numerous modifications and delays for the class in general.^[2]

U-23 was an ocean-going submarine that displaced 173 tonnes (191 short tons) surfaced and 210 tonnes (231 short tons) submerged and was designed for a complement of 18. She was 127 feet 2 inches (38.76 m) long with a beam of 13 feet (4.0 m) and a draft of 9 feet (2.7 m). For propulsion, she featured a single shaft, a single 450 bhp (340 kW) diesel engine for surface running, and a single 160 shp (120 kW) electric motor for submerged travel.^[3] She was capable of 12 knots (22 km/h) while surfaced and 9 knots (17 km/h) while submerged. Although there is no specific notation of a range for U-23, the Havmanden class, upon which the U-20 class was based, had a range of 1,400 nautical miles (2,600 km) at 10 knots (19 km/h), surfaced, and 23 nautical miles (43 km) at 8 knots (15 km/h) submerged.^[6]

U-23 was armed with two 45 cm (17.7 in) torpedo tubes located in the front and carried a complement of two torpedoes. She was also equipped with a 66 mm (2.6 in)/26 deck gun and an 8 mm (0.31 in) machine gun.^[3]

Service career

U-23 was launched on 5 January 1917,^[3] but It is not known with certainty when U-23 was commissioned. Author Paul Halpern reports that U-23 and her three sisters all entered service between August and November 1917.^[4] Although there are no specific reports of problems with U-23, the U-20 class as a whole suffered from unreliable engines which compounded the poor handling characteristics of the boats.^[4] On 21 February 1918,^[8] Linienschiffsleutnant Klemens Ritter von Bezard, U-23's only commanding officer,^[5] was guiding the boat in an attack on the Italian transport Memfi in the Straits of Otranto. U-23 came under attack by the Italian torpedo boat Airone which first tried to ram the U-boat, and then deployed an explosive paravane. When the paravane contacted the submerged U-23, it exploded, blowing debris into the air and sinking the submarine with all hands.^[8] Like all of her sister boats,^[2] U-23 had no wartime successes.^[5]

References

^ ^a ^b ^c ^d Halpern, p. 382.
^ ^a ^b ^c ^d ^e Gardiner, p. 344.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ Gardiner, p. 343.
^ ^a ^b ^c ^d Halpern, p. 383.
^ ^a ^b ^c ^d Helgason, Guðmundur. "WWI U-boats: KUK U23". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 29 November 2008.
^ ^a ^b ^c Gardiner, p. 354.
^ ^a ^b Gardiner, p. 341.
^ ^a ^b Grant, p. 163.

Bibliography

Gardiner, Robert; Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships 1906–1921. Annapolis, Maryland: Naval Institute Press. ISBN 978-0-87021-907-8. OCLC 12119866.
Gibson, R. H.; Prendergast, Maurice (2003) [1931]. The German Submarine War, 1914–1918. Annapolis, Maryland: Naval Institute Press. ISBN 978-1-59114-314-7. OCLC 52924732.
Grant, Robert M. (2002) [1964]. U-boats Destroyed: The Effect of Anti-submarine Warfare, 1914–1918. Penzance: Periscope. ISBN 978-1-904381-00-6. OCLC 50215640.
Halpern, Paul G. (1994). A Naval History of World War I. Annapolis, Maryland: Naval Institute Press. ISBN 978-0-87021-266-6. OCLC 28411665.