David invaded Northumberland at the very beginning of the year. Already castles were arising, and he failed to take Wark, but wasted the open country, his hordes of wild mountaineers committing terrible atrocities. Stephen hastened northward, and David retreated; but the English king, with rebellion in the south, could only waste Lothian and withdraw. David thereupon reassembled his forces and again advanced. Norham Castle was taken, Wark again besieged, the levies of Lancashire defeated by the King’s nephew William at Clitheroe, and the Scottish host poured over Tees into Yorkshire. There it encountered solid resistance. Its barbarities had exasperated the country-folk, and they rallied _en masse_ to oppose the invaders. The nominal commander-in-chief was the young William of Albemarle, but Thurstan, Archbishop of York, and Sir Walter Espec, the High Sheriff, were the real leaders. The men of Yorkshire, with reinforcements from Durham, Derby, and Nottingham, assembled at Northallerton, and took up a position on Cowton Moor some distance to the northward. On August 22 they were attacked by the Scots. David had with him a heterogeneous host from all parts of his dominions--said, with considerable probability, to have been 26,000 strong. But it was very unstable. The Picts of Alban were jealous of the ‘Saxons’ of Lothian, and neither were inclined to work well with the Britons of Strathclyde. The Niduarian Picts of Galloway were uncontrollable, and all the old elements of the realm disliked the new Norman-Teutonic immigrants, although their small force of about 500 mailed horsemen was to show itself the one thoroughly reliable arm of the host. The English army was, without any doubt, greatly inferior in number, as is shown by the fact that it maintained a passive defensive--the last plan of action likely to be adopted by the fiery Norman-English knights unless there had been compelling reason for it. The bulk of the force consisted of the country levies, but the whole knighthood of Yorkshire were there, and there was a strong contingent of archers. Albemarle and Espec formed their army into one solid mass, probably with the mail-clad knights and their followers dismounted as a front rank. In the centre of the line was a waggon with a tall mast stepped in it, from which flew the sacred banners of St. Peter of York, St. Cuthbert of Durham, St. Wilfrid of Ripon, and St. John of Beverley; and beneath their shadow old Walter Espec and Albemarle took their stand, with a band of chosen warriors as a guard. The horses were sent to the rear, and the barons and knights promised to stand and die with the country-folk.