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
Feudal barony of Dunster who was a "powerful personage" due to her large Wyndham dowry, purchased Dunster Priory following the Dissolution of the Monasteries, which thenceforth descended with the castle. By his wife Margaret Wyndham he had children including three sons: Sir John Luttrell (died 1551), of Dunster Castle, eldest son and heir. He was one of the principal commanders in the Scottish war under the earl of Hertford. In 1545 he was knighter after the capture of Leith. He was taken prisoner by the Scots in 1550 at Broughty Craig and was ransomed for £400. He married Mary Ryce, daughter of Sir Griffith