The revolts which broke out in the north and southwest compelled him to return to England in December. Early in 1068 he marched on Exeter, as the centre of the western revolt. He took the town and built a castle, after which he subdued Cornwall, and then marching northward forced Bristol to submit. In the summer of 1068 there was a general rising of the North, of which Eadgar was the nominal head; but Eadwine and Morkere were the moving spirits. The insurgents were aided by Malcolm, King of Scotland. William had, however, only to show himself in order to put down the insurrection. He journeyed northward, by way of Warwick and Nottingham, to York, received the submission of Eadwine, Morkere, and Malcolm, and returned by way of Lincoln and Cambridge. His march was accompanied by heavy confiscations, and great castles, rising in places of vantage, rendered the Norman power at once visible and secure. In the spring of 1069 a fresh revolt broke out. Robert of Comines, the newly appointed Earl of Northumberland, was slain at Durham; a Danish fleet entered the Humber, and a Danish army, joined by Eadgar and Waltheof, seized and burned York. The sons of Harold attacked Devon, while other isolated outbreaks took place in the west. These were speedily put down by William's lieutenants; and in the autumn the king himself, going northward a second time, recovered York, and harried Northumberland with ruthless deliberation. Returning to keep Christmas at York, he set out again in January, 1070, to oppose Malcolm, who had crossed the border in aid of the insurgents. He forced Waltheof to submit, and drove the Scottish king back into his own country; then, marching over pathless fells in the depth of winter, he reached Chester, took the town, and founded another castle. [Illustration: William at Hastings.] Northumbria, exhausted and ruined, gave up the struggle, and the omission of the northern counties from the Domesday survey throws a grim light on the completeness of the Conquest. In one district only, the fens of Cambridgeshire, where Hereward still held out, the spirit of resistance survived. In April, 1071, William arrived at Cambridge and commenced a regular blockade. Advancing cautiously by means of a causeway through the fens, he entered Ely in October, and therewith the last flicker of independence died out. The conquest of England was completed. To guard against any fresh incitements to rebellion from Scotland, William in 1072 invaded that country and forced Malcolm to do him homage--an event which had an important effect on the subsequent relations of the two countries.