Complex sentence: At the end of the war he joined the Freikorps in Silesia and fought against the Polish forces, his unit was later incorporated into the Reichswehr as the 16th Cavalry Regiment and Simon was promoted to Unterfeldwebel.
Split into simpler sentences: At the end of the war he joined the Freikorps in Silesia and fought against the Polish forces. His unit was later incorporated into the Reichswehr as the 16th Cavalry Regiment and Simon was promoted to Unterfeldwebel.