In March 978, King Edward was assassinated at Corfe Castle, possibly at the instigation of his stepmother, and Æthelred the Unready became king. His coronation on Low Sunday 31 March 978, was the last state event in which Dunstan took part. According to William of Malmsesbury, writing over a century later, when the young king took the usual oath to govern well, Dunstan addressed him in solemn warning. He criticised the violent act whereby he became king and prophesied the misfortunes that were shortly to fall on the kingdom, but Dunstan's influence at court was ended. Dunstan retired to Canterbury, to teach at the cathedral school.