German submarine U-135 (1941)

German submarine U-135 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.

She was laid down at the Vulkan-Vegesackerwerft in Bremen on 16 September 1940 as yard number 14, launched on 12 June 1941 and commissioned on 16 August with Oberleutnant zur See Friederich-Hermann Praetorius in command.

U-135 began her service career in training with the 5th U-boat Flotilla, before moving on to the 7th flotilla for operations.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-135 had a displacement of 769 t when at the surface and 871 t while submerged. She had a total length of 67.10 m, a pressure hull length of 50.50 m, a beam of 6.20 m, a height of 9.60 m, and a draught of 4.74 m. The submarine was powered by two MAN M 6 V 40/46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2800 to 3200 PS for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 double-acting electric motors producing a total of 750 PS for use while submerged. She had two shafts and two 1.23 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 17.7 kn and a maximum submerged speed of 7.6 kn. When submerged, the boat could operate for 80 nmi at 4 kn; when surfaced, she could travel 8500 nmi at 10 kn. U-135 was fitted with five 53.3 cm torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, and a 2 cm C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history
The boat sank three ships totalling and damaged a fourth of.

First and second patrols
The submarine's first patrol began with her departure from Kiel on 24 December 1941. Her route took her across the North Sea and into the Atlantic Ocean via the passage between the Orkney and Shetland Islands. As part of wolfpack 'Ziethen', she sank Gandia on 22 January 1942 420 nmi east of Cape Race, (Newfoundland). She arrived at St. Nazaire in occupied France on the 31st.

Her second foray was northeast of Iceland, but she returned to another port, Brest, on 3 April 1942.

Third and fourth patrols
Her third sortie was her longest, at 71 days. Having departed Brest on 26 April 1942, she sank Fort Qu Appelle on 17 May north of Bermuda. She also sank Pleasantville on 8 June northwest of Bermuda before returning to St. Nazaire on 5 June.

U-135 discovered and shadowed convoy ON 122 during her fourth patrol, and was able to remain on patrol following heavy damage received when attacked with depth charges and Hedgehog by HNoMS Potentilla and HMS Viscount (D92). The boat was later attacked by a Czech-crewed Vickers Wellington aircraft of No. 311 Squadron RAF on 3 October 1942 in the Bay of Biscay. Only minor damage was sustained, but one man was killed and another died of his wounds.

Fifth and sixth patrols
Her fifth sortie took her across the Atlantic, almost to the coast of Newfoundland.

U-135's sixth patrol was toward Greenland; she was attacked by a British B-24 Liberator of 120 Squadron northeast of Ireland on 8 February 1943. Some damage was repaired, but the boat was forced to return to Lorient on 10 March when further leaks were discovered.

Seventh patrol and loss
For her last patrol, she left Lorient on 7 June 1943. Northeast of the West Indies, she attacked and damaged Twickenham on the 15th. She then moved to the east Atlantic where she was attacked by the sloop HMS Rochester (L50), the corvettes HMS Migonette (K38) and HMS Balsam (K72) and a US PBY Catalina flying boat of VP-92. U-135 was sunk east of the Canary Islands on 15 July. Five men died, there were 41 survivors.

Wolfpacks
U-135 took part in ten wolfpacks, namely:
 * Zieten (6 – 20 January 1942)
 * Westwall (2 – 12 March 1942)
 * York (12 – 25 March 1942)
 * Pfadfinder (21 – 27 May 1942)
 * Lohs (17 August - 20 September 1942)
 * Panzer (23 November - 11 December 1942)
 * Raufbold (11 – 19 December 1942)
 * Pfeil (3 – 8 February 1943)
 * Neptun (18 – 28 February 1943)
 * Trutz 2 (22 – 29 June 1943)