U47 Gunter Prien Sank Royal Oak. in Scapa Flow.
U99 Otto Kretschmer wrote book The Upturned Horseshoe he was captured and taken prisoner and held in Canada and later held a senior position in NATO. He believed in one torpedo, one boat.
Lehmann-Willenbrock and U-96:
Quote.
•He commanded the Type VIIB German submarine U-96 from 1940 to 1942, taking it on several combat patrols during the Battle of the Atlantic.
• Inspiration for Das Boot: His wartime experiences aboard U-96—where he served alongside war correspondent Lothar-Günther Buchheim—directly inspired Buchheim's famous novel Das Boot and its classic film adaptation.
I think if you re-read my post you will see what was meant.
regards
Roy