Complex sentence: Elimar's descendants appear as vassals, although sometimes rebellious ones, of the dukes of Saxony; but they were given the title of princes of the empire when the emperor Frederick I dismembered the Saxon duchy in 1189.
Split into simpler sentences: Elimar's descendants appear as vassals, although sometimes rebellious ones, of the dukes of Saxony. They were given the title of princes of the Empire when the emperor Frederick I dismembered the Saxon duchy in 1189.