The fall of York gave a serious aspect to the case, and called for William's presence. Soon after the capture of the city the Danes had gone back to the Humber, to the upper end of the estuary apparently, and there they succeeded in avoiding attack by crossing one river or another as the army of the king approached. In the meantime, in various places along the west of England, insurrections had broken out, encouraged probably by exaggerated reports of the successes of the rebels in the north. Only one of these, that in Staffordshire, required any attention from William, and in this case we do not know why. In all the other cases, in Devon, in Somerset, and at Shrewsbury, where the Welsh helped in the attack on the Norman castle, the garrisons and men of the locality unassisted, or assisted only by the forces of their neighbours, had defended themselves with success. If the Danish invasion be regarded as a test of the security of the Conquest in those parts of England which the Normans had really occupied, then certainly it must be regarded as complete. Prom the west William returned to the north with little delay, and occupied York without opposition. Then followed the one act of the Conquest which is condemned by friend and foe alike. When William had first learned of the fate of his castles in York, he had burst out into ungovernable rage, and the mood had not passed away. He was determined to exact an awful vengeance for the repeated defiance of his power. War in its mildest form in those days was little regulated by any consideration for the conquered. From the point of view of a passionate soldier there was some provocation in this case. Norman garrisons had been massacred; detached parties had been cut off; repeated rebellion had followed every pacification. Plainly a danger existed here, grave in itself and inviting greater danger from abroad. Policy might dictate measures of unusual severity, but policy did not call for what was done, and clearly in this case the Conqueror gave way to a passion of rage which he usually held in check, and inflicted on the stubborn province a punishment which the standard of his own time did not justify.