Stephen marched on Oxford, crossed the river at the head of his men, routed the Queen's supporters, and set fire to the city. Matilda shut herself up in the Castle and prepared to resist the attacks of the King. But Stephen prosecuted the siege with great vigour; every approach to the Castle was carefully guarded, and after three months the garrison was reduced to the greatest straits. Provisions were exhausted; the long-looked-for succour never came; without, Stephen pushed the siege harder than ever. It seemed certain that Matilda must fall into his hands. Her capture would be the signal for the collapse of the rebellion. But just as the end seemed inevitable, Matilda managed to escape in marvellous wise. There had been a heavy fall of snow; so far as the eye could see from the Castle towers the earth was hidden beneath a thick white pall. The river was frozen fast. The difficulty of distinguishing a white object on this white background, and the opportunity of crossing the frozen river by other means than that of the guarded bridge, suggested a last faint chance of escape. Matilda's courage rose to the occasion. She draped herself in white, and with but one companion stole out of the beleaguered Castle at dead of night, and made her way, unseen, unheard through the friendly snow. Dry-footed she stole across the river, and gradually the noise of the camp faded away into the distance behind her. For six weary miles she stumbled on through the heavy drifts of snow, until at last she arrived in safety at Wallingford. The bird had flown, and the Castle shortly afterwards surrendered to the baffled King (_Gesta Stephani_). During this siege the people were deprived of the use of the Church of S. George, and to supply their spiritual needs a new church sprang into existence. It was dedicated to S. Nicholas, and afterwards to S. Thomas a Becket. Of the original church, just opposite the L. & N.W. Railway Station, part of the chancel remains. The tower is fifteenth century. The Castle mill is mentioned in the Domesday Survey. The present mill no doubt occupies the same site; its foundations may preserve some of the same masonry as that which is thus recorded to have existed hereabouts before the Conquest.