Fregattenkapitän Heinrich Lehmann-Willenbrock was a submarine commander in Germany during World War II and the subject of the mini-series called "Das Boot" when he was portrayed by which actor? 
Heinrich Lehmann-Willenbrock: Fregattenkapitän Heinrich Lehmann-Willenbrock (11 December 1911 – 18 April 1986) was a submarine commander in the "Kriegsmarine" of Nazi Germany during World War II. Heinrich Lehmann-Willenbrock:  The story of the "U-96" was eventually made into a mini-series and film called "Das Boot", in which he was portrayed by Jürgen Prochnow. Das Boot: Das Boot (] , German meaning "The Boat") is a 1981 German war film written and directed by Wolfgang Petersen, produced by Günter Rohrbach, and starring Jürgen Prochnow, Herbert Grönemeyer, and Klaus Wennemann.
Jürgen Prochnow