In the Barons' War of 1215–17 the castle was attacked again, prompting further improvements in its defences.[1] In 1220 Falkes de Breauté, who controlled many royal castles in the middle of England, demolished the Church of St Budoc to the south-east of the castle and built a moated barbican to further defend the main gate.[34] The remaining wooden buildings were replaced in stone, including the new Round Tower which was built in 1235.[35] King Henry III turned part of the castle into a prison, specifically for holding troublesome University clerks, and also improved the castle chapel, replacing the older barred windows with stained glass in 1243 and 1246.[36] Due to the presence of Beaumont Palace to the north of Oxford, however, the castle never became a royal residence.[37]