Complex sentence: Barkhorn joined the Bundesluftwaffe in 1956, rose to command JaboG 31 "Boelcke" and retired in 1976 with the rank of "Generalleutnant".
Split into simpler sentences: Barkhorn joined the Bundesluftwaffe in 1956, rose to command JaboG 31 "Boelcke". He retired in 1976 with the rank of "Generalleutnant".