Gerhard Groth was my uncle so I have some personal knowledge her. After he was the executive officer on the U-boat depicted in Das Boot he became commander of his own U-boat and became the youngest U-boat commander in the German navy. It was later in the war so the technology and tide had turned against easy "gains" by U-boats. However, he did sink two ships one of which was an ammunition ship. Years later when he spoke about this it was always with deep anguish. He also stated that he searched for and tried to assist survivors. At the end of the war he alone took his U-boat out to sea and sank it. Reports are that he was highly regarded. A further note is that he was quite anti-nazi and this is an important factor that led him to enlist in the navy since the navy was evidently quite independent from politics. After WW II he returned to Mexico where he lived the rest of his life and had a small company related to photography exports/imports. I knew him as an extremely principled, proper, restrained man who was psychologically deeply wounded by the war. In many ways he was an old world, international gentlemen. He rarely if ever spoke about what he had experienced in WW II. He never married and died when a truck hit him in 1998.

A further note is that the book, Das Boot, was derived from an amalgamation of a journalist who visited three different U-boats one of which was my uncle. Evidently the journalist was extremely supportive of the Nazis. I hope this information was useful.