Complex sentence: But in the eloquent words Manthor turned Hardang's mistreating of Húrin to his undoing, and the Men of Brethil besieged him and his followers in the Hall of the Chieftains.
Split into simpler sentences: But in the eloquent words, Manthor turned Hardang's mistreating of Húrin to his undoing. The Men of Brethil besieged him and his followers in the Hall of the Chieftains.