Complex sentence: Harald Scharff (1836--1912) was a ballet dancer associated with the Royal Danish Theatre in the middle nineteenth century who succeeded August Bournonville as the Danish ballet's principal male dancer upon the latter's retirement from the stage.
Split into simpler sentences: Harald Scharff (1836--1912) was a ballet dancer associated with the Royal Danish Theatre in the middle nineteenth century. He succeeded August Bournonville as the Danish ballet's principal male dancer upon the latter's retirement from the stage.