This anarchy began to assume a form when Robert of Gloucester, alleging his previous oath to Matilda, and asserting that the conditions on which he had accepted Stephen had not been kept, renounced his fealty. His influence was in his earldom, and in the West of England; the headquarters of his party was Bristol; and his agent during his absence was Milo, Constable of Gloucester, afterwards Earl of Hereford. Nearly all the West, and by no means the West only, declared for Matilda. But in most cases the rival claims to the throne were used as an excuse merely. Change of sides was common, and there are instances of leaders excluding their own nominal partisans from strongholds they had won.[14] At first the insurrection was unsuccessful. Stephen, conscious of his weakness, had collected mercenaries from Flanders and from Brittany. The condition of the country made them eager to come. In Stephen’s time numbers of freebooters from Flanders and Brittany flocked to England in expectation of pillage.[15] The chief leader of the Flemings was William of Ypres; the Bretons were commanded by Alan the Black of Richmond, Hervé of Léon, and Alan of Dinan. With the aid of these Stephen speedily regained the great castles he had lost, such as Bath, Castlecary, Harptree, and Shrewsbury; and might perhaps even yet have established his authority, when an act of supreme folly set him at variance with the Church. [Sidenote: Jealousy between the old and new administration.] The new administrative class was represented by Roger of Salisbury, who had succeeded in procuring for his nephew Alexander the bishopric of Lincoln, for Nigel the bishopric of Ely, while his illegitimate son Roger was Chancellor. The vast wealth and influence of this family encouraged them to build castles, and Devizes, Sherborne, Malmesbury, and Salisbury were strongly fortified. The family of Beaumont, Earls of Mellent, had been generally firm supporters of the crown and of authority. They now seem to have seen with jealousy their position as the chief advisers to the crown occupied by men of law, ecclesiastics, yet without the sanctity which befits the ecclesiastical profession. At their instigation, and at that of their friends, the King took the ill-advised step of beginning his assault on his castle-building barons by demanding the surrender of these bishops’ castles. The Bishops of Lincoln and Salisbury were suddenly arrested at an assembly held at Oxford (1139); the Bishop of Ely took refuge in the castle of Devizes. Thither the King betook himself, with his two prisoners, as some accounts assert, kept entirely without food, one in a cow-stall and the other in a hovel. This treatment of the bishops, and a threat of hanging Roger the Chancellor, produced the surrender of Devizes as well as the other three castles. [Sidenote: Stephen’s quarrel with the Church.] [Sidenote: Consequent arrival of Matilda. Sept. 30, 1139.]