Lewes Priory was founded by William de Warenne and his wife Gundrada between 1078 and 1082 on the site of a Saxon church dedicated, like the Priory, to St Pancras. William was a leading Norman baron with extensive lands in Sussex and elsewhere in England. He also founded Castle Acre Priory in Norfolk. Lewes was the first Priory in England belonging to the reformed Benedictine Order of Cluny, based in France. It became one of the wealthiest monasteries in England. However, in spite of its wealth it played little role in national affairs, except at the time of the Battle of Lewes in 1264 when it was occupied by the troops of King Henry III.The main buildings, including the great Priory church, were put up in Quarr limestone in the Romanesque style between c1082 to c1100 and in Caen limestone from c1145 to the 13th century. Repairs and additions continued up to the monastery's dissolution in November 1537. At this time it owned over 20,000 acres in Sussex with other lands elsewhere, was the patron of 19 parish churches in the county and owned two houses for the poor in Lewes. Dominating the site was the great church, with a nave 432 feet long, larger than Chichester Cathedral.