Complex sentence: The other strongholds were Borgvold in Viborg, Bygholm in Horsens and Ulstrup east of Struer and they were all build by enrolled local peasant slavery workers, in order to break their rebellious spirit.
Split into simpler sentences: The other strongholds were Borgvold in Viborg, Bygholm in Horsens and Ulstrup east of Struer. They were build by enrolled local peasant slavery workers, in order to break their rebellious spirit.