Henry strove to carry out the new policy without respect for rank or party; but when he threatened the strongholds of the great nobles his difficulties began. Hugh Mortimer and Roger, son of Milo Earl of Hereford and High Constable, old supporters of Matilda, refused to surrender Wigmore, Cleobury, Bridgenorth, Hereford, and Gloucester. Henry at once took action. Leaving Wallingford Castle in the spring of 1155, he laid siege to Bridgenorth, whence one of his letters is dated “apud Brugiam in obsidione.” He also took by siege Cleobury and Wigmore. This success caused the Earl of Hereford to surrender Hereford and Gloucester, where Henry had received much of his education; and on his protestation of submission, the Earl was allowed to retain Hereford. Henry, Bishop of Winchester, Stephen’s brother, was forced to flee the country, and his castles were ordered to be destroyed; and that this order was executed appears from the charge for the work entered in the Pipe Roll for 1155-6. In like manner D’Aumâle, a baron of the house of Champagne, whose power lay in Holderness, and who had commanded at Northallerton, was forced, in January, 1155, after a short resistance, to give up Scarborough, the strongest castle in Holderness, and Skipsea, not far its inferior. Henry also visited Northampton, Nottingham, Lincoln, and York, and some of the western castles and counties. At Windsor the “fermor” of the castle expended £4. 15s. 5d. in his reception “in corredio regis.” According to Mr. Eyton, 140 castles were destroyed in the course of 1155. William of Ypres, a turbulent leader of Flemish mercenaries, who had been created Earl of Kent by Stephen in 1141, was banished. He was one of the “pseudo Comites.” A part of the new policy, though not at once enforced, was the introduction, to a certain extent, of a money commutation for personal military service. The new payment, under the name of “scutage,” became an important branch of the revenue of the Crown. A rule was also established, which, if not always acted upon, was well understood, that no man should build a castle, or convert his dwelling into a “domus defensabilis,” without a licence from the King.