Complex sentence: Rettemeier worked in the steel industry before joining the Bundeswehr in 1956, after that he led panzer regiments and brigades, then served as X.O. in panzer and jäger divisions.
Split into simpler sentences: Rettemeier worked in the steel industry before joining the Bundeswehr in 1956,. After that he led panzer regiments and brigades, then served as X.O. in panzer and jäger divisions.