sentences:  German submarine U-309
  
  German submarine "U-309" was a Type VIIC U-boat of Nazi Germany's "Kriegsmarine" during World War II.The submarine was laid down on 24 January 1942 at the Flender Werke yard at Lübeck, launched on 5 December 1942, and commissioned on 27 January 1943 under the command of "Oberleutnant zur See" Hans-Gert Mahrholz.