Complex sentence: When Hitler became Chancellor of Germany in January 1933, Fuchs decided to leave Kiel, where the NSDAP was particularly strong, and he was a well-known KPD member, and he enrolled at the Kaiser Wilhelm Institute for Physics in Berlin.
Split into simpler sentences: When Hitler became Chancellor of Germany in January 1933, Fuchs decided to leave Kiel, where the NSDAP was particularly strong and he was a well-known KPD member. He enrolled at the Kaiser Wilhelm Institute for Physics in Berlin.