German submarine U-138 (1940)

German submarine U-138 was a Type IID U-boat of Nazi Germany's Kriegsmarine in World War II. Her keel was laid down on 16 November 1939 by Deutsche Werke in Kiel as yard number 267. She was launched on 18 May 1940 and commissioned on 27 June 1940 with Oberleutnant zur See Wolfgang Lüth in command.

U-138 conducted five patrols, sinking six ships totalling and damaged one vessel of.

She was scuttled on 18 June 1941 after being damaged by British warships west of Cadiz in Spain. There were no casualties from her crew of 28.

Design
German Type IID submarines were enlarged versions of the original Type IIs. U-138 had a displacement of 314 t when at the surface and 364 t while submerged. Officially, the standard tonnage was 250 LT, however. The U-boat had a total length of 43.97 m, a pressure hull length of 29.80 m, a beam of 4.92 m, a height of 8.40 m, and a draught of 3.93 m. The submarine was powered by two MWM RS 127 S four-stroke, six-cylinder diesel engines of 700 PS for cruising, two Siemens-Schuckert PG VV 322/36 double-acting electric motors producing a total of 410 PS for use while submerged. She had two shafts and two 0.85 m propellers. The boat was capable of operating at depths of up to 80 - 150 m.

The submarine had a maximum surface speed of 12.7 kn and a maximum submerged speed of 7.4 kn. When submerged, the boat could operate for 35 - 42 nmi at 4 kn; when surfaced, she could travel 3800 nmi at 8 kn. U-138 was fitted with three 53.3 cm torpedo tubes at the bow, five torpedoes or up to twelve Type A torpedo mines, and a 2 cm anti-aircraft gun. The boat had a complement of 25.

First patrol
U-138 departed Kiel on her first patrol on 10 September 1940. Her route took her through the Kattegat and Skagerrak before entering the North Sea. She then reached her area of operations off western Scotland and northern Northern Ireland after negotiating the gap between the Faroe and Shetland Islands.

Her first victim was New Sevilla, quickly followed by Boka and City of Simla. The three ships all went down 52 nmi north-west of Rathlin Island on 20 September. The following day, she hit Empire Adventure. The ship sank while under tow by HMS Superman.

The boat docked in Lorient on the French Atlantic coast on 26 September.

Second patrol
For her second foray, U-138 sank Bonheur and damaged British Glory on 15 October 1940 northwest of the Butt of Lewis in the Outer Hebrides. British Glory was repaired and returned to service in January 1942.

Third patrol
Patrol number three involved another passage west of the British Isles so that the submarine could safely dock in Kiel, but she did not add to her score.

Fourth patrol
The boat returned to Lorient on 27 May 1941, having sunk Javanese Prince on the 20th.

Fifth patrol
U-138 was attacked by the British destroyers HMS Faulknor (H62), HMS Fearless (H67), HMS Forester (H74), HMS Foresight (H68) and HMS Foxhound (H69) west of Cadiz, Spain, on 18 June 1941. The resulting damage forced the crew to abandon ship and scuttle the U-boat. There were no casualties amongst her crew of 28, who were taken prisoner-of-war and brought to Gibraltar.