Fairfax ordered the castle to be totally destroyed under the supervision of Henry Herbert, a descendant of William ap Thomas. The fortifications proved too strong, however, and only a few of the walls were destroyed, or slighted. Historian Matthew Johnson describes the event as having the atmosphere of a "community festival", as local people dredged the castle moat in search of treasure, and emptied the fishponds of valuable carp. The castle's library, including an important collection of Welsh documents and books, was either stolen or destroyed.