Dunster Castle the north; a third force, under the command of William de Mohun, landed by sea along the Somerset coast. William had been granted 68 manors in the region and by 1086 had established a castle at Dunster; this would form both the "caput", or principal castle, for his new lands, and help guard the coast against the threat of any fresh sea-borne attack, as well as controlling the coastal road running from Somerset to Gloucestershire. This first castle was a motte and bailey design, built upon the former Anglo-Saxon "burgh"; the top of the Tor was scarped to form the
Dunster Castle during the early 12th century, probably forming a shell keep around the top of the motte. In the late 1130s England began to descend into a period of civil war known as the Anarchy, during which the supporters of King Stephen fought with those of the Empress Matilda for control of the kingdom. William de Mohun's eldest son, also called William, was a noted supporter of Matilda, and Dunster was considered one of her faction's strongest castles in the south-west. In 1138 forces loyal to Stephen besieged the castle; a siege castle was built nearby, but all trace of it