Complex sentence: Augusta von Fersen, "as married Löwenhielm," (1754--1846), was a Swedish noblewoman and lady-in-waiting, a well known figure in the Gustavian court and a royal mistress to Charles XIII of Sweden.
Split into simpler sentences: Augusta von Fersen, "as married Löwenhielm," (1754--1846), was a Swedish noblewoman and lady-in-waiting. She was a well known figure in the Gustavian court and a royal mistress to Charles XIII of Sweden.