Complex sentence: The MS "St. Louis" was a German ocean liner most notable for a single voyage in 1939, in which its captain, Gustav Schröder, tried to find homes for over 900 Jewish refugees from Germany.
Split into simpler sentences: The MS "St. Louis" was a German ocean liner. In 1939, it set off on a voyage in which its captain, Gustav Schröder, tried to find homes for over 900 Jewish refugees from Germany.