In 1075 Waltheof joined the Revolt of the Earls against William I. His motives for taking part in the revolt are unclear, as is the depth of his involvement. However he repented, confessing his guilt first to Archbishop Lanfranc and then in person to William I, who was at the time in Normandy. He returned to England with William but was arrested, brought twice before the king's court and sentenced to death.