In the midst of this critical state of affairs, Henry landed at Southampton in July, 1174, with his prisoners, whom he sent to Devizes. His arrival coincided with a sudden and material improvement in the state of his affairs. While Henry was engaged in an act of penance at Becket’s tomb, William, King of Scots, was taken before Alnwick. After a short illness in London, Henry went to Huntingdon in time to receive the surrender of the castle, and thence to Framlingham, which, with Bungay, was surrendered to him by Hugh Bigot. Prince Rhys, then in alliance with Henry, besieged and took Tutbury, and the Mowbray castle of Malzeard was also taken. At Northampton, in July, Henry received the submission of the Bishop of Durham, with the castles of Durham, Norham, and Northallerton. Thirsk Castle was given up by Roger de Mowbray; Tutbury and Driffield by Earl Ferrars, with Leicester, Mount Sorrell, and Groby. Henry’s success was complete; but the rebellion showed how dangerous were the great castles to public order, and how necessary it was to dismantle a large number of them, and to keep the rest, as far as possible, in the hands of the Crown. This policy he continued to act upon to the end of his reign, treating all conquered rebels with great clemency as regarded their persons and their estates, but retaining their castles in his own hands. Even Richard de Lacy, to whom the hundred of Ongar was granted in 1174, was not allowed to retain the castle. In May, 1175, Henry was in England, and in June received the surrender of Bristol Castle from William, Earl of Gloucester. In January, 1176, was held the council at Northampton, at which the kingdom was divided into six circuits, with three justiciaries for each circuit. Among the edicts which they were to enforce were those relating to castles. A strict inquisition was to be made into the tenure by castle-guard, and how far its duties were discharged. It does not appear to what extent the new regulations were carried out; but the general effect of the new system was to check marauders, and to render insurrections more difficult and less frequent. Northallerton, more than once dismantled, was at last (1177) entirely destroyed; and the Bishop of Durham, its owner, had to pay a fine of a thousand marcs for his share in the last rebellion. Such castles as Durham, Norham, and Scarborough, which it was expedient to preserve, were attached to the Crown, and placed in the hands of faithful castellans. Bamburgh was entrusted to William de Stuteville, and Norham to William de Neville, Scarborough to the Archbishop of York, Berwick to Geoffrey de Neville, and Durham to Roger de Coniers. The assize of arms, by which, in 1180, it became the duty of each freeholder to provide himself with arms and armour according to his means and condition, rendered the commonalty more capable of resisting tyranny, and on the whole tended to strengthen the hands of any not very unpopular sovereign against the barons.