Norman Conquest Encyclopedia

In 1064 William the Bastard moved against a force under Conan II, ruler of Brittany, who had been engaged in operations against Breton rebels under Riwallon of Dol. Riwallon appealed to William who relieved Dol-de-Bretagne, near the coast north of Rennes, forcing Conan to move south. William went on to take Dinan and the Bayeux Tapestry shows a castle on a motte there. There is no evidence of such a castle on the ground, but the importance of the position, on a plateau high above the River Rance, controlling the country inland of St Malo, and thus access to northern Brittany, is evident.

Related Reading:

• Hastings 1066 (Revised Edition)- The Fall of Saxon England
  (Campaign 13 )