German submarine U-400 was a Type VIIC U-boat of the German Navy (Kriegsmarine) during World War II. The submarine was laid down on 18 November 1942 at the Howaldtswerke yard in Kiel as 'werk' 32, launched on 8 January 1944 and commissioned on 18 March under the command of Kapitänleutnant Horst Creutz.