Complex sentence: The U-boat was known to them as "der Seiltänzer" ("the Tightrope Walker"), and her crew painted an emblem of a yellow shield with a red horse on her sail during their final patrol.
Split into simpler sentences: The U-boat was known to them as "der Seiltänzer" ("the Tightrope Walker"). Her crew painted an emblem of a yellow shield with a red horse on her sail during their final patrol.