# German submarine U-991

German submarine U-991 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.

## Construction

The U-991 was laid down on 30 October 1942 at the Blohm & Voss yard in Hamburg, Germany. She was launched on 24 June 1943 and commissioned on 29 July 1943 under the command of Oberleutnant zur See Diethelm Balke. Her U-boat emblem was a diving eagle.
When she was completed, the submarine was 67.10 metres (220 ft 2 in) long, with a beam of 6.18 metres (20 ft 3 in), a height of 9.60 metres (31 ft 6 in) and a draft of 4.74 metres (15 ft 7 in). She was assessed at 864.7 t (851 long tons) submerged. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2,800 to 3,200 metric horsepower (2,060 to 2,350 kW; 2,760 to 3,160 shp) for use while surfaced and two BBC GG UB 720/8 double-acting electric motors producing a total of 750 metric horsepower (550 kW; 740 shp) for use while submerged. She had two shafts and two 1.23 m (4 ft) propellers. The submarine was capable of operating at depths of up to 230 metres (750 ft), had a maximum surface speed of 17.6 knots (32.6 km/h; 20.3 mph) and a maximum submerged speed of 7.5 knots (13.9 km/h; 8.6 mph).When submerged, the U-boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph) and when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph).
The submarine was fitted with five 53.3 cm (21 in) torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm (3.46 in) deck gun (220 rounds) and a 3.7 cm (1.5 in) Flak M42 anti-aircraft gun. The boat had a complement of 44 to 57 men.

## Service history

U-991 was used as a Training ship in the 5th U-boat Flotilla from 29 July 1943 until 31 August 1944 before serving in the 11th U-boat Flotilla for active service on 1 September 1944.

### Training and tests

During U-991's service as a training ship, she completed a number of trainings and tests for the Kriegsmarine.
| Date | Place | Activity |
| 30 July – 19 August 1943 | Keel | Trials at UAK |
| 20 August 1943 | Sonderborg | Auscultation at UAK |
| 22 – 26 August 1943 | Swinemünde | Flakausbildung at Flakschule |
| 27 – 29 August 1943 | Danzig | Trials at UAK |
| 30 August – 4 September 1943 | Hela | Front training at AGRU-Front |
| 5 September 1943 – 5 February 1944 | Flensburg | School boat |
| 9 February – 11 May 1944 | Hela | Front training at AGRU-Front |
| 12 – 23 May 1944 | Pillau | Torpedo shooting at the 26th U-boat Flotilla |
| 24 May – 4 June 1944 | Gotenhafen | Tactical Training at the 27th U-boat Flotilla |
| 5 – 8 June 1944 | Baltic Sea | March over Königsberg to Stettin. Equipment for the company Wallenstein |
| 10 June – 14 August 1944 | Königsberg | Remaining work in F. Schichau yard |
| 15 – 16 August 1944 | Danzig | Trials at UAK |
| 21 – 26 August 1944 | Swinemünde | Flakausbildung at Flakschule |
| 29 August – 12 September 1944 | Königsberg | Installation of a Schnorchel underwater-breathing apparatus |
| 13 – 20 September 1944 | Hela | Snorkel training at AGRU-Front |
| 21 – 22 September 1944 | Rönne | Auscultation at AUK |
| 23 – 29 September 1944 | Keel | Remaining work and equipment to the 1st company |

### Active Service

During her active service, U-991 made 1 patrol and left Kristiansand on 15 October 1944. Her patrol lasted 73 days and U-991 patrolled the North Atlantic from Norway, around the United Kingdom and Ireland and also to France before returning to Bergen. She arrived in Bergen on 26 December 1944, which marked the end of her first and only patrol during World War II.
| Date | Port of Departure | Port of Arrival | Duration |
| 5 – 7 October 1944 | Kiel | Horten | 3 days |
| 11 – 12 October 1944 | Horten | Kristiansand | 2 days |
| 15 October – 26 December 1944 | Kristiansand | Bergen | 73 days (Patrol) |
| 27 – 29 December 1944 | Bergen | Marviken | 3 days |
| 2 – 4 January 1945 | Marviken | Flensburg | 3 days |
| 20 – 27 April 1945 | Kiel | Horten | 8 days |
| 29 April – 4 May 1945 | Horten | Bergen | 6 days |
In total, the U-991 spend 98 days at sea during her active service until 9 May 1945.

## Capture And End

U-991 surrendered on 9 May 1945 at Bergen, Norway to the Allied Forces. The submarine was transferred from Bergen to Scapa Flow on 2 June 1945 and from Scapa Flow to Loch Ryan on 5 June 1945. She stayed in Loch Ryan for her immersion in Operation Deadlight (post-war Allied operation) until 11 December 1945, when she was towed to sea by the British Navy tug HMS Freedom (W.139).
U-991 was sunk at 12.15am on 11 December 1945 in the North Atlantic, North-West off the coast of Ireland by a torpedo from the British submarine HMS Tantivy. Her wreck still lies at 56°10′N 10°05′W﻿ / ﻿56.167°N 10.083°W﻿ / 56.167; -10.083.