Plan Z
"U-109" was ordered by the "Kriegsmarine" on 24 May 1938 (as part of Plan Z and in violation of the Treaty of Versailles). Her keel was laid down on 9 March 1940 by DeSchiMAG AG Weser, Bremen as yard number 972. "U-109" was launched on 14 September 1940 and commissioned on 5 December under the command of Hans-Georg Fischer.