William de Mohun of Dunster, 1st Earl of Somerset William de Mohun of Dunster, 1st Earl of Somerset William de Mohun of Dunster, Earl of Somerset (c. 1090 – c. 1155), 2nd feudal baron of Dunster, was a favourite of Empress Matilda and a loyal supporter of her in the war against King Stephen, during which he earned the epithet of the "Scourge of the West". William was the son of William de Moion, who was seigneur of Moyon which is close to Saint-Lô. The elder William was High Sheriff of Somerset in 1084. During the war between Matilda and Stephen, Stephen marched against Mohun's castle at Dunster, but
Dunster Castle including the south-west. In the case of Dunster, Thomas's son George Luttrell was able to convince the authorities to destroy only the medieval defensive walls, rather than the entire castle, leaving Dunster damaged from the recent siege but still habitable; the walls were demolished over 12 days in August 1650 by a team of 300 workmen. The only parts of the medieval walls to survive were the Great Gatehouse and the bases of the two towers in the Lower Ward. George Luttrell died without children, and Dunster Castle passed to his brother Francis, who survived the political turmoil of both