|Ordered:||20 January 1941|
|Laid down:||12 November 1942|
|Launched:||4 December 1943|
|Commissioned:||22 January 1944|
|Fate:||Sunk in the English Channel, March 1945|
|Class and type:||Type VIIC submarine|
|Height:||9.60 m (31 ft 6 in)|
|Draught:||4.74 m (15 ft 7 in)|
|Complement:||4 officers, 40–56 enlisted|
|Operations:||6 February – 26 March 1945|
She carried out one patrol. She sank one ship and caused another to be declared a total loss.
She was sunk in the English Channel in March 1945.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-399 had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged. She had a total length of 67.10 m (220 ft 2 in), a pressure hull length of 50.50 m (165 ft 8 in), a beam of 6.20 m (20 ft 4 in), a height of 9.60 m (31 ft 6 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 Garbe, Lahmeyer & Co. RP 137/c 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 17.7 knots (32.8 km/h; 20.4 mph) and a maximum submerged speed of 7.6 knots (14.1 km/h; 8.7 mph). When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph). U-399 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), one 3.7 cm (1.5 in) Flak M42 and two twin 2 cm (0.79 in) C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.
The submarine was laid down on 12 November 1942 at the Howaldtswerke (yard) at Kiel as yard number 31, launched on 4 December 1943 and commissioned on 22 January 1944 under the command of Oberleutnant zur See Kurt van Meteren.
Patrol and loss
U-399 departed Horten on 6 February 1945. On 21 March, she torpedoed the Liberty ship James Eagan Layne "about twelve miles off Plymouth". The ship was beached at nearby Whitesand Bay but settled on the bottom; at high water, only her masts and funnel showed. She was declared a total loss.
The boat sank the Dutch-registered Pacific on 26 March 1945. This ship had taken part in Operation Dynamo, the Dunkirk evacuation, in 1940.
Forty-six men died in U-399; there was one survivor.
Summary of raiding history
|21 March 1945||James Eagan Layne||United States||7,176||Total loss|
|26 March 1945||Rosenborg||Netherlands||362||Sunk|
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