Brothers Ilbert and Walter de Lacy jointly held the Norman lands of the Bishop of Bayeux. They participated in the Norman conquest of England. While there is evidence that Ilbert fought at William's side at Hastings, there is no record of Walter fighting at Hastings. Ilbert was a major participant in the Harrying of the North (1069–70) which effectively ended the quasi-independence of the region through large-scale destruction that resulted in the relative "pacification" of the local population and the replacement of local Anglo-Danish lords with Normans. In return, he received vast grants of land in West Yorkshire, where he built Pontefract Castle.