Complex sentence: Evidently a natural pilot, upon graduating he was immediately enrolled as an instructor, before departing to the front where he had to serve with Kampfstaffel 20 of Kampfgeschwader IV as an observer before he could earn his pilot's badge.
Split into simpler sentences: Evidently a natural pilot, upon graduating, he was immediately enrolled as an instructor, before departing to the front. He had to serve with Kampfstaffel 20 of Kampfgeschwader IV as an observer before he could earn his pilot's badge.