first settlement. Wallingford has been fortified since the Anglo-Saxon period when it was an important fortified borough of Wessex with the right to mint royal coinage. It was enclosed with substantial earthworks by King Alfred the Great in the ninth century as part of a network of fortified towns known as burhs, or burghs, to protect Wessex against the Vikings. These defences can still be clearly discerned as a group of four roughly square areas around the centre of the town and are well-preserved. Wallingford became the chief town of Berkshire and the seat of the county's Ealdorman. Medieval period During the Norman conquest in 1066, the Anglo-Saxon lord Wigod allowed William the Conqueror's invading armies into Wallingford to rest and to cross the Thames unopposed. It is in Wallingford that Stigand the Archbishopric of Canterbury surrendered and submitted to William, thereby all but ending opposition to William's ascent to the throne. From Wallingford, William with Stigand and his armies rode east to Berkhamsted, where he received the final surrender from Edgar and the rest of the English leadership before marching on London for his coronation on Christmas Day. At that time, the river at Wallingford was the lowest point at which the river could be forded. The town subsequently stood in high favour with the Normans as Wallingford Castle was built soon afterward on the orders of William, and became a key strategic centre controlling the Thames crossing and surrounding area. The Domesday Book of 1085 lists Wallingford as one of only 18 towns in the kingdom with a population of over 2,000 people. Establishment of Wallingford Priory (1097) Wallingford Priory, also known as Holy Trinity Priory, is believed to have stood on the site of the Bull Croft recreation ground off the High Street. This Benedictine priory was established on land granted to St Albans Abbey in 1097 by Henry I, and Geoffrey the Chamberlain gave the priory to St Albans Paul, 14th Abbot of St Albans, who sent some of his monks to establish a cell there. Wallingford Priory produced the mathematician Richard of Wallingford and the chronicler John of Wallingford. The Anarchy and King John (12th century) Wallingford provided refuge for the Empress Matilda's party during the civil war that began after her father Henry I's death. After the fall of Oxford Castle to Stephen in 1141, Matilda fled to Wallingford, according to some historic accounts