German submarine U-406

German submarine U-406 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 6 September 1940 by Danziger Werft, Danzig as yard number 107, launched on 16 June 1941 and commissioned on 22 October 1941 under Oberleutnant zur See Horst Dietrichs.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-406 had a displacement of 769 t when at the surface and 871 t while submerged. She had a total length of 67.10 m, a pressure hull length of 50.50 m, a beam of 6.20 m, a height of 9.60 m, and a draught of 4.74 m. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2800 to 3200 PS for use while surfaced, two Siemens-Schuckert GU 343/38–8 double-acting electric motors producing a total of 750 PS for use while submerged. She had two shafts and two 1.23 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 17.7 kn and a maximum submerged speed of 7.6 kn. When submerged, the boat could operate for 80 nmi at 4 kn; when surfaced, she could travel 8500 nmi at 10 kn. U-406 was fitted with five 53.3 cm torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, and an anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history
The boat's career began with training at 8th U-boat Flotilla on 22 October 1941, followed by active service on 1 May 1942 as part of the 7th Flotilla for the remainder of her service.

In eight patrols she sank one merchant ship, for a total of, and three merchant ships for a total of.

Wolfpacks
U-406 took part in eleven wolfpacks, namely
 * Hecht (8 May – 18 June 1942)
 * Blücher (14–28 August 1942)
 * Iltis (6–23 September 1942)
 * Spitz (22–31 December 1942)
 * Neuland (4–13 March 1943)
 * Dränger (14–20 March 1943)
 * Drossel (29 April – 5 May 1943)
 * Rügen (14–26 January 1944)
 * Stürmer (26 January – 3 February 1944)
 * Igel 1 (3–17 February 1944)
 * Hai 1 (17–18 February 1944)

Fate
U-406 was sunk on 18 February 1944 in the North Atlantic in position 48.53333°N, -23.6°W, by depth charges from Royal Navy frigate HMS Spey (K246). Twelve of the crew were killed.