Name U-99 Yard number 593 Commissioned 18 April 1940 Launched 12 March 1940 Draft 4.74 m | Ordered 15 December 1937 Laid down 31 March 1939 Construction started 31 March 1939 Length 67 m Beam 6.2 m | |
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Part of Kriegsmarine, 7th U-boat Flotilla | ||
German submarine U-99 was a Type VIIB U-boat of Nazi Germany's Kriegsmarine during World War II. She was laid down on 31 March 1939 at the Friedrich Krupp Germaniawerft in Kiel as yard number 593. She was launched on 12 March 1940 under the command of Korvettenkapitän Otto Kretschmer and was assigned to the 7th U-boat Flotilla based in Kiel and later in St Nazaire.
Contents
- Design
- Service history
- 1st patrol
- 2nd patrol
- 3rd patrol
- 4th patrol
- 5th patrol
- 6th patrol
- 7th patrol
- 8th patrol
- Fate
- Wolfpack operations
- References
U-99 was one of the most successful German U-boats in the war, sinking 38 ships for a total tonnage of 244,658 gross register tons (GRT) of Allied shipping in eight patrols. She damaged five more ships and took one vessel as a prize.
Design
German Type VIIB submarines were preceded by the shorter Type VIIA submarines. U-99 had a displacement of 753 tonnes (741 long tons) when at the surface and 857 tonnes (843 long tons) while submerged. She had a total length of 66.50 m (218 ft 2 in), a pressure hull length of 48.80 m (160 ft 1 in), a beam of 6.20 m (20 ft 4 in), a height of 9.50 m (31 ft 2 in), and a draught of 4.74 m (15 ft 7 in). 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, 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 boat was capable of operating at depths of up to 230 metres (750 ft).
The submarine had a maximum surface speed of 17.9 knots (33.2 km/h; 20.6 mph) and a maximum submerged speed of 8 knots (15 km/h; 9.2 mph). When submerged, the boat could operate for 90 nautical miles (170 km; 100 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,700 nautical miles (16,100 km; 10,000 mi) at 10 knots (19 km/h; 12 mph). U-99 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) SK C/35 naval gun, 220 rounds, and one 2 cm (0.79 in) anti-aircraft gun The boat had a complement of between forty-four and sixty.
Service history
From April to June 1940, the crew of U-99 were under training, based at Kiel and St. Nazaire.
1st patrol
On 18 June, U-99 departed Kiel for operations in the North Sea west of Norway. She was attacked by an Arado Ar-196 seaplane from the German battleship Scharnhorst, having been mistaken for a British submarine. Two days later, U-99 was attacked by two aircraft; minor damage was inflicted. She returned to Kiel on 25 June.
2nd patrol
U-99 departed Wilhelmshaven on 27 June to patrol southwest of Ireland. On 29 June, she was attacked by British aircraft. A crash dive was carried out with the result that the boat hit the seabed, causing some damage which was able to be repaired. During this patrol, U-99 sank six ships. A seventh was captured. An attack on the 5,360 GRT Manistee was called off on 7 July, when the armed merchant ship fired upon the U-boat. On 8 July, over 100 depth charges were dropped by the escorts of Convoy HX 53, but U-99 escaped undamaged. The patrol ended on 21 July.
† Convoy HX 52, ‡ Convoy HX 53, * sunk by German bombing, 15 July 1940
3rd patrol
On 25 July, U-99 departed Lorient for the North Atlantic. Four ships were sunk and three others damaged. On the 31st, the escorts of Convoy OB 191 dropped 20 depth charges on the boat without effect. Later that evening, a flying boat also attacked her, again without causing any damage. The patrol ended on 5 August.
† Convoy OB 191, ‡ Damaged
4th patrol
U-99 departed Lorient on 4 September for the North Atlantic; seven ships were sunk. The patrol ended on the 25th. U-99 was slightly damaged in an air raid on Lorient on 27 September.
† Convoy SC 3, ‡ Convoy HX 71, * Convoy HX 72
5th patrol
On 13 October, U-99 departed Lorient to patrol the North West Approaches. Six ships from Convoy SC 7 were sunk and another was damaged. The patrol ended on 22 October.
6th patrol
U-99 departed Lorient for the North West Approaches on 30 October 1940; four ships were sunk. The patrol ended on 8 November.
† Convoy HX 83
7th patrol
On 27 November, U-99 departed Lorient for the North Atlantic. Four ships were sunk. The patrol ended on 12 December.
† Convoy HX 90, ‡ Convoy OB 252
8th patrol
U-99 departed Lorient on 22 February 1941 to patrol in the North Atlantic; eight ships were sunk. U-99 was attacked herself, with severe damage inflicted. Kretschmer surrendered and scuttled the submarine with the loss of three lives.
† Convoy OB 293, ‡ Convoy HX 112
Fate
On 17 March 1941, U-99 had just fired the last of her torpedoes and sunk Korshamn when the Watch Officer spotted a destroyer, south-east of Iceland in approximate position 61°N 12°W. He immediately ordered a dive, contrary to Kretschmer's standing orders, but once the boat was under it was quickly fixed on ASDIC and attacked by HMS Walker and Vanoc. U-99 was driven deep by the attack but was nonetheless severely damaged. Kretschmer had no choice but to surface; immediately a barrage of fire greeted the boat. Kretschmer sent a message to Donald Macintyre, Walker's captain, "CAPTAIN TO CAPTAIN. I AM SUNKING [sic] PLEASE RESCUE MY CREW." He then ordered that the boat should be scuttled. Forty crew, including Kretschmer, were rescued to become POWs. Three crewmen - the engineering-officer and two ratings - lost their lives. The engineering officer re-entered the sinking U-boat and perished while opening the galley hatch, to hasten the boat's sinking and prevent the British from boarding it.
Macintyre took Kretschmer's binoculars as a souvenir.
Wolfpack operations
U-99 operated with the following Wolfpacks during her career: