The castle was then the scene of an infamous massacre. Over Christmas 1175 De Braose called Seisyll and his son Geoffrey to his castle, together with other leaders from Gwent, supposedly as an act of reconciliation. De Braose then had the men killed in the castle's great hall, in retribution for the death of Henry Fitzmiles. His action, including taking the men's land, resulted in sanctions: William was "retired" from public life and the castle passed to his son, William. In 1182 Hywel ap Iorwerth, lord of Caerleon, ordered the destruction of Dingestow Castle and had Abergavenny Castle set afire in retribution for the murder of Seisyll. The attacks were made by Seisyll's relatives. De Braose was not at the castle when it was burnt, but "most of his men" were taken hostage.