Wallingford Castle Wallingford Castle was a major medieval castle situated in Wallingford in the English county of Oxfordshire ( historically in Berkshire until the 1974 reorganisation ) , adjacent to the River Thames . Established in the 11th century as a motte - and - bailey design within an Anglo - Saxon " burgh " , it grew to become what historian Nicholas Brooks has described as " one of the most powerful royal castles of the 12th and 13th centuries " . Held for the Empress Matilda during the civil war years of the Anarchy , it survived multiple sieges and was never taken . Over the next two centuries it became a luxurious castle , used by royalty and their immediate family . After being abandoned as a royal residence by Henry VIII , the castle fell into decline . Refortified during the English Civil War , it was eventually slighted , i . e . deliberately destroyed , after being captured by Parliamentary forces after a long siege . The site was subsequently left relatively undeveloped , and the limited remains of the castle walls and the considerable earthworks are now open to the public . History . 11th century . As an important regional town , overlooking a key crossing point on the River Thames , prosperous and with its own mint , the town of Wallingford had been defended by an Anglo - Saxon " burgh " , or town wall , prior to the Norman invasion of 1066 . Wigod of Wallingford , who controlled the town , supported William the Conqueror ' s invasion and entertained the king when he arrived in Wallingford . Immediately after the end of the initial invasion , the king set about establishing control over the Thames Valley through constructing three key castles , the royal castles of Windsor and Wallingford , and the baronial castle , later transferred to royal hands , built at Oxford . Wallingford Castle was probably built by Robert D ' Oyly between 1067 and 1071 . Robert had married Wigod ' s daughter Ealdgyth , and ultimately inherited many of his father - in - law ' s lands . The wooden castle was built in the north - east corner of the town , taking advantage of the old Anglo - Saxon ramparts , with the motte close to the river overlooking the ford , and required substantial demolition work to make room for the new motte - and - bailey structure . Unusually , it appears that the castle was constructed on top of high - status Anglo - Saxon housing , probably belonging to former housecarl s . The motte today is 60 metres ( 197 feet ) across and 13 metres ( 43 feet ) high . Robert endowed a sixteen - strong college of priests within the castle , which he named St Nicholas College . 12th century . Wallingford Castle passed from Robert to first his son - in - law Miles Crispin , and then Brien FitzCount , who married Robert ' s daughter after Miles died . Brien , an important supporter of Henry I , was the son of the Duke of Brittany , and probably strengthened the castle in stone in the 1130s . He produced a very powerful fortification , including a shell keep and a curtain wall around the bailey , that , combined with the extensive earthworks , has been described by historian Nicholas Brooks as " one of the most powerful royal castles of the 12th and 13th centuries " . After the death of Henry , however , the political situation in England became less stable , with both Stephen of England and the Empress Matilda laying claim to the throne . Brien had originally been considered a supporter of Stephen , but in 1139 Matilda travelled to England and Brien announced his allegiance to her , joining forces with Miles of Gloucester and other supporters in the south - west . Wallingford Castle was now the most easterly stronghold of the Empress ' s faction – it was either the closest base to London , or the first in line to be attacked by Stephen ' s forces , depending on one ' s perspective . Stephen attacked the castle in 1139 , initially intending to besiege it , as the walls were considered impregnable to assault . Brien had brought in considerable supplies – contemporaries believed the castle could survive a siege for several years if need be – and Stephen changed his mind , putting up two counter - castles to contain Wallingford along the road to Bristol , before continuing west . The next year , Miles of Gloucester , possibly acting under orders from Robert of Gloucester , struck east , destroying one of the counter - castles outside Wallingford . The civil war between Stephen and Matilda rapidly descended into an attritional campaign , in which castles like Wallingford played a critical role in efforts by both sides to secure the Thames Valley . After the fall of Oxford to Stephen in 1141 , Matilda fled to Wallingford , and the importance of the castle continued to grow . Around this time Brien established a notorious prison within the castle , called " Cloere Brien " , or " Brien ' s Close " , as part of his efforts to extract money and resources from the surrounding region . The nobleman William Martel , Stephen ' s royal steward , was one of the most high profile prisoners to be kept there . Contemporary chroniclers reported the cries of tortured prisoners in the castle disturbed the inhabitants of the town of Wallingford . There was not enough space in the castle for all of Brien ' s forces , and various houses in the town had to be taken for the use of his knights . Between 1145 and 1146 Stephen made another attempt to seize Wallingford , but was again unable to take the castle despite building a powerful counter - castle to the east , opposite Wallingford at Crowmarsh Gifford , and building castles to the west at Brightwell , South Moreton and Cholsey . He returned with larger forces in 1152 , reestablishing the counter - castle at Crowmarsh Gifford and building another one overlooking Wallingford bridge , and settled his forces down to starve the castle out . Brien , supported by Miles ' son , Roger of Hereford , who had also become trapped in the castle , attempted to break through the blockade , but without success . By 1153 , the castle garrison was running very low on food , and Roger made a deal with Stephen allowing him to leave the castle with his followers . Henry , the Empress ' son and the future Henry II , then intervened , marching his forces to relieve the castle and placing Stephen ' s counter - castles under siege himself . King Stephen marched back from Oxford , and the two forces confronted each other on the meadows outside the castle . The result was an embryonic peace deal called the Treaty of Wallingford , leading on to the permanent Treaty of Winchester that would ultimately bring an end to the civil war and install Henry as king following Stephen ' s death in 1153 . Brien , who had no children , chose to enter a monastery , and surrendered Wallingford Castle to Henry at the end of the conflict in 1153 . At the end of the 12th century , the castle become closely associated with King John , who had been granted the town by Richard I in 1189 . John seized the castle as well during his revolt in 1191 , and although he was forced to return it , he reclaimed it when he became king himself in 1199 . John made extensive use of Wallingford Castle during the First Barons ' War between 1215 and 1216 , reinforcing the fortifications and mobilising a substantial garrison to protect it . 13th – 15th centuries . Under Henry III , Richard , the 1st Earl of Cornwall was formally granted the castle as his main residence in 1231 . Richard lived in considerable style , and spent substantial sums on the property , building a new hall and more luxurious fittings . Richard ' s election as King of the Romans in 1251 brought an end to his use of the property , but the castle became embroiled in the Second Barons ' War in the 1260s . Simon de Montfort seized the castle after his victory at the battle of Lewes , using it to imprison the royal family for a time , before moving them to the more secure Kenilworth Castle . Reclaimed by Henry III at the end of the conflict , it continued to be used by the Earls of Cornwall as a luxurious home for the rest of the century . Edward II gave Wallingford Castle first to his royal favourite , Piers Gaveston , and then to his young wife , Isabella of France , with large sums still being spent on the property . Edward continued to use the castle as a royal prison for holding his enemies , until his own fall from power in 1326 ; Isabella , who overthrew her husband , then used it as an early headquarters following her invasion of England . Her son , Edward III , ultimately settled the castle on the new title of the Duke of Cornwall , used by sons of the king . The castle continued to be used as a county jail , with many complaints about the number of felons who were able to escape from it . The cost of maintaining the castle from local rents and revenues became more challenging towards the end of the 14th century , with additional royal revenues being required for the ongoing work required on it . Nonetheless , in 1399 when Richard II was deposed , the castle was well fortified and in good condition , forming what historian Douglas Biggs calls " a formidable obstacle " to Richard ' s enemies , and able to host the royal government when it first fled from London . Wallingford Castle played little role in the Wars of the Roses and after Henry VIII used it for a final time in 1518 it appears to have fallen into disuse as a royal residence . 16th – 19th centuries . The castle fell into decline in the 16th century ; it was separated from the Duchy of Cornwall , and under Queen Mary the site was stripped for lead and other building materials for use at Windsor Castle . The antiquarian John Leland described the castle in 1540 as being " nowe sore yn ruine , and for the most part defaced " , although the jail continued in use throughout the period , albeit still suffering from many escapee inmates . Held by various nobles from 1600 onwards , it returned to the crown under Charles I , who gave it to Queen Henrietta Maria , but by then the castle was only really valuable for the surrounding meadow land and fisheries . The English Civil War broke out between the supporters of Charles I and Parliament in the 1640s ; with the king and Parliament maintaining their capitals in Oxford and London respectively , the Thames Valley once again became a critical war zone . Wallingford was a Royalist town , with a garrison established there in 1642 to prevent an advance on Oxford to the north - west . Colonel Thomas Blagge was appointed governor , and in 1643 the king instructed him to refortify the castle , inspecting the results later that year . By 1644 , the surrounding Thames towns of Abingdon and Reading had fallen and Parliamentary forces unsuccessfully attacked the town and castle of Wallingford in 1645 . General Thomas Fairfax placed Wallingford Castle under siege the next year ; after 16 weeks , during which Oxford fell to Parliamentary forces , the castle finally surrendered on July 1646 under generous terms for the defenders . The risk of civil conflict continued , however , and Parliament decided that it was necessary to slight , or damage so as to put beyond military use , the castle in 1652 , as it remained a surprisingly powerful fortress and a continuing threat should any fresh uprising occur . The castle was virtually razed to the ground in the operation , although a brick building continued to be used as a prison into the 18th century . A large house was built in the bailey in 1700 , followed by a gothic mansion house on the same site in 1837 . Today . The mansion , abandoned due to rising costs , was demolished in 1972 , allowing Wallingford Castle to be declared a scheduled monument as well as a Grade I listed building . The castle grounds , including the remains of St Nicholas College , two sections of castle wall and the motte hill , are now open to the public . An archaeological research project run by Leicester University conducted a sequence of excavations between 2002 and 2010 , aiming to better understand the historical transition from the Anglo - Saxon town of Wallingford and the " burgh " , to the period of the Norman castle .