The Romans built the fortress around 250AD as an anchorage for their ships and to protect the nearby city of Anderida, which gave the castle its name. In AD491, the fortress fell before the onslaught of the Saxon warlord, Aelle and everyone within was slaughtered. In 1066, William camped briefly within the walls on his way to the fateful Battle of Hastings. After the Conquest, a Norman castle was built within the walls and was besieged three times, first by William Rufus, Stephen and then Simon de Montford and gallantly defended by Lady Joan Pelham.