Adolf Cornelius Piening (16 September 1910 – 15 May 1984) was a Kapitänleutnant with the Kriegsmarine during World War II. He commanded the Type IXC U-boat U-155, sinking twenty-six ships on nine patrols, for a total of 140,449 gross register tons (GRT) of Allied shipping, to become the nineteenth highest scoring U-Boat ace of World War II. received the Knight's Cross of the Iron Cross. which was awarded to recognise extreme battlefield bravery or successful military leadership.