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. She served with the
5th U-boat Flotilla from 22 January 1944 and the
11th flotilla from 1 February 1945. The boat's first patrol was preceded by the short journey from
Kiel in Germany to
Horten Naval Base (south of Oslo), arriving at the Norwegian port on 28 January 1945.
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.
U-399 was sunk later on the same day by
depth charges from the British
frigate . Forty-six men died in
U-399; there was one survivor. ==Summary of raiding history==