Complex sentence: In 1930 he left the "Grenzschutz", joined the Nazi Party, and became a member of the SS in 1931, achieving the rank of SS- "Brigadeführer" in late 1933.
Split into simpler sentences: In 1930 he left the "Grenzschutz", and joined the Nazi Party. He became a member of the SS in 1931, achieving the rank of SS- "Brigadeführer" in late 1933.