Question: 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? 
Sentence (from "Heinrich Lehmann-Willenbrock"): He commanded four U-boats, and his most successful tour was commanding the "U-96" a Type VIIC U-boat, which gained widespread recognition when one of its patrols was documented and publicized by an accompanying member of a propaganda company Lothar-Günther Buchheim.
Relevant evidence: No