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.