Complex sentence: General Von Dietrich was not only a military general, but also a doctor who took tattooing as a hobby--he enjoyed tattooing the bodies of young girls and showing them to his guests at parties.
Split into simpler sentences: General Von Dietrich was not only a general, but he was also a medical doctor who did tattooing as a hobby. He enjoyed tattooing the bodies of young girls and showing them to his guests at parties.