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. 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.