German submarine U-371

German submarine U-371 was a Type VIIC U-boat of the Nazi German Kriegsmarine during World War II. The submarine was laid down in November 1939 in Kiel, launched in January 1941, and commissioned in March under the command of Oberleutnant zur See Heinrich Driver. After training, U-371 was ready for front-line service with the 1st U-boat Flotilla from 1 July 1941.

Operating mostly in the Mediterranean Sea, in 19 patrols between June 1941 and May 1944 the U-boat sank 13 ships totalling 67,573 tons, including the American destroyer USS Bristol (DD-453), and damaged six more totalling 30,572 tons.

U-371 was sunk at 04:09 local time on 4 May 1944 in the Mediterranean north of Constantine, in position 37.81667°N, 5.65°W by a force of American, French and British destroyers. Three men were killed, there were 49 survivors.

Construction and Design
U-371 was ordered by the Kriegsmarine on 23 September 1939. She was laid down about two months later at the Howaldtswerke yard in Kiel, on 17 November. Just over a year and two months later, U-371 was launched on 27 January 1941. She was formally commissioned later that year on 15 March. U-371 carried 5 × 533 mm torpedo tubes (four located in the bow, one in the stern) and had one C35 88mm/L45 deck gun with 220 rounds. She could also carry 14 G7e torpedoes or 26 TMA mines and had a crew of 44-52 men.

1st patrol
U-371 left Kiel on 5 June 1941, under the command of Kapitänleutnant Heinrich Driver, and sailed out into the north Atlantic. She sank two merchant ships; the British 6,373 ton Silverpalm on 12 June and the Norwegian 4,765 ton Vigrid on 24 June, before arriving at Brest in France on 1 July.

2nd patrol
The U-boat sailed from Brest on 23 July 1941 to patrol between the coast of Portugal and the Azores. Early on 30 July she sank two more merchant ships south-east of the Azores, both from Convoy OS-1; the British 6,935 ton Shahristan, and the Dutch 7,049 ton Sitoebondo. She returned to Brest on 19 August.

3rd patrol
U-371 departed from Brest on 16 September 1941, sailing south, and then through the Strait of Gibraltar into the Mediterranean Sea. After patrolling the coast of Egypt, the U-boat arrived at Salamis in Greece on 24 October, having had no successes, officially transferring to the 23rd U-boat Flotilla on 1 November.

4th and 5th patrols
U-371 carried out two more patrols along the coast of Egypt and in the Eastern Mediterranean from December 1941 to January 1942 and again in March 1942, but sank no ships.

6th patrol
Now part of the 29th U-boat Flotilla, U-371 left Salamis again on 21 April 1942 under the temporary command of Kapitänleutnant Heinz-Joachim Neumann, and headed south to the coast of Egypt. However on 7 May the U-boat was depth charged by two submarine chasers and was so badly damaged that she had to return to base. She arrived back at Salamis on 9 May.

7th patrol
Command of U-371 was now assumed by Kapitänleutnant Waldemar Mehl, who took the U-boat from Salamis to Pola, Venezia Giulia, in early July, not sailing on a combat patrol until 5 September when he took the U-boat along the length of the Adriatic Sea, and through the eastern Mediterranean to the coast of British Palestine and French Syria, arriving back at Salamis on 18 September, and returning to Pola in mid-October.

8th and 9th patrols
The U-boat left Pola and sailed to Messina in Sicily on 1–4 December 1942, leaving on 7 December to attack the Allied shipping off the coast of French Algeria after "Operation Torch", the invasion of North Africa. There, on 7 January 1943, she attacked Convoy MKS-5, sinking the British naval trawler HMS Jura (T169), and later the same day damaged the 7,159 ton British troopship Ville de Strasbourg. The U-boat then sailed to La Spezia in north-western Italy, arriving on 10 January 1943.

10th patrol
The Algerian coast now became U-371's hunting ground, and she left La Spezia on 14 February 1943 to return there to sink the unescorted 2,089 ton British merchant ship Fintra on 23 February, and to damage the 7,176 ton American liberty ship Daniel Carroll from Convoy TE-16, before returning to La Spezia on 3 March.

11th patrol
U-371 departed La Spezia again on 7 April 1943, once more heading to the Algerian coast, where she sank the 1,162 ton Dutch merchant ship Merope on 27 April, before heading to her new home port of Toulon in southern France on 11 May 1943.

12th patrol
After leaving Toulon on 3 July 1943, on the 10th, U-371 attacked Convoy ET-22A, damaging two American ships; the 6,561 ton tanker Gulfprince and the 7,176 ton liberty ship Matthew Maury, returning to Toulon on the 12th.

13th and 14th patrol
U-371's next patrol lasted from 22 July until 11 August 1943, during which she sank the 6,004 ton British merchant ship Contractor, part of Convoy GTX-5. U-371 patrolled again from 21 August to 3 September 1943, but made no successful attacks.

15th patrol
Leaving Toulon on 7 October 1943, U-371 once more haunted the Algerian coast, sinking the British minesweeper HMS Hythe (J194) on 11 October, the American destroyer USS Bristol (DD-453) on the 13th, and on the 15th torpedoed the American liberty ship James Russell Lowell, damaging her so badly that she was declared a total loss. The U-boat returned to base on 28 October.

16th and 17th patrols
The U-boat's next patrol was short, lasting from 15 to 23 November 1943, and was unsuccessful. Her 17th patrol began on 22 January 1944, and took her to the western coast of Italy after the launching of "Operation Shingle", the Allied landings at Anzio. She made no successful attacks and returned to Toulon on 13 February.

18th patrol
U-371 departed Toulon on 4 March 1944 and returned to the Algerian coast. On the 17th she attacked Convoy SNF-17, sinking the 17,024 ton Dutch troopship Dempo, and badly damaging the 6,165 ton American C2 cargo ship Maiden Creek, which later broke in two after being beached. The U-boat returned to Toulon on 25 March. Three days later, U-371's commander, Waldemar Mehl, received the Knight's Cross of the Iron Cross, before leaving the U-boat to serve on the staff of FdU Mittelmeer ("U-boat Command Mediterranean"). On 5 April command of U-371 passed to Oberleutnant zur See Horst-Arno Fenski, former commander of GS U-410.

19th patrol
Under Fenski's command, U-371 left Toulon for the final time at about 19:00 at on 23 April 1944, and headed back to the coast of Algeria, patrolling from 10 to 15 miles offshore.

On 28 April U-371 received a report of a large convoy and set course to intercept it. On the night of 2 May the U-boat planned to surface in order to top up her batteries by running on her diesel engines, as she expected to contact the convoy within a few hours. Unfortunately on doing so, she found herself almost in the middle of the convoy, and immediately crash-dived to about 100 m. After an hour the U-boat surfaced again and headed toward the convoy, but was soon detected by the American destroyer escort USS Menges (DE-320). As the US ship closed to 3000 m U-371 fired a T-5 acoustic torpedo from her stern tube, and immediately dived. The Menges was hit; the aft third of the vessel was destroyed, killing 31 men and wounding 25. However she remained afloat and was towed to Bougie in Algeria and later repaired and returned to service.

U-371 was now unlucky enough to be the first victim of an Allied submarine hunting tactic called "Swamp". This called for the area of a known or suspected U-boat to be packed with escort ships and patrol aircraft. They would then systematically and continually search the area, forcing the U-boat to remain submerged until its batteries ran out or it tried to escape on the surface. Either option was almost hopeless. U-371 found herself being relentlessly hunted by the American destroyer escorts USS Pride (DE-323) and USS Joseph E. Campbell (DE-70), the Free French FFL Sénégalais and L'Alcyon, and the British HMS Blankney (L30).

When U-371 first attempted to surface after crippling the Menges, depth charges forced her back down, while putting out all the lights, damaging the hydroplanes, and rupturing the trim tanks. The U-boat levelled off at about 200 - 215 m, leaking badly. The depth charge attacks continued at about 30-minute intervals, with increasing accuracy, and the U-boat sustained further damage.

At around 06:00 on 3 May, U-371 attempted to evade ASDIC (sonar) detection by lying on the sea floor. This would also conserve battery power, which was becoming dangerously low. She lay on the sea-bed at around 240 m for the rest of the day, hoping that the attackers would give up the hunt. Late that night though, the surface vessels could still be heard, but with the air quality in the boat rapidly deteriorating, the emergency lighting system out, and having taken on about 15 tons of water, the U-boat's commander decided that their only hope was to surface and attempt to escape in the darkness.

Blowing her ballast tanks only attracted the attention of the attackers, which began dropping depth charges again, and the U-boat was still stuck. The crew had to run from one end of the U-boat to the other while the engines ran at full power in order to break the grip of the mud before the U-boat finally began to surface. All torpedo tubes were loaded and readied for firing, and all guns were manned when U-371, with her batteries practically exhausted, surfaced and ran for safety.

After fifteen minutes the enemy was seen coming up astern, immediately opening fire and scoring several hits. The U-boat returned fire, but the situation was clearly hopeless and most of her crew jumped overboard. As a last show of defiance the U-boat fired a T-5 acoustic torpedo from her stern tube, and managed to hit the Sénégalais, causing some damage.

By this time, around 04:00 on 4 May 1944, only the commander Horst-Arno Fenski, the Engineering Officer and a control room petty officer remained aboard. The latter two remained below to flood the tanks, which caused U-371 to sink so rapidly that they were unable to escape and the both drowned.