Complex sentence: Hans-Arnold Stahlschmidt (September 15,1920-missing in action September 7 1942) was a German fighter pilot of the highest calibre, and a close friend of the famous desert ace Hans-Joachim Marseille, (158 Kills).
Split into simpler sentences: Hans-Arnold Stahlschmidt, born September 15,1920; missing in action September 7 1942, was a German ace fighter pilot. Stahlschmidt was a close friend of the prominent ace Hans-Joachim Marseille (158 Kills).