The barons who had promised to protect the Empress gathered at Wallingford, but did not venture to attempt a direct raising of the siege. Robert of Gloucester returned from Normandy about December 1, but Stephen allowed him to win a small success or two, and kept steadily to his purpose. As it drew near to Christmas provisions became low in the castle, and the necessity of surrender unpleasantly clear. Finally Matilda determined to attempt a bold escape. It was a severe winter and the ground was entirely covered with snow. With only a few attendants--three and five are both mentioned--she was let down with ropes from a tower, and, clad all in white, stole through the lines of the besiegers, detected only by a sentry, who raised no alarm. With determined spirit and endurance she fled on foot through the winter night and over difficult ways to Abingdon, six miles away. There she obtained horses and rode on to Wallingford, where she was safe. The castle of Oxford immediately surrendered to Stephen, but the great advantage for which he had striven had escaped him when almost in his hands. Robert of Gloucester, who was preparing to attempt the raising of the siege, at once joined his sister at Wallingford, and brought with him her son, the future Henry II, sent over in place of his father, on his first visit to England. Henry was now in his tenth year, and for four years and more he remained in England in the inaccessible stronghold of Bristol, studying with a tutor under the guardianship of his uncle. Robert's mission of the previous summer, to get help for Matilda in England, proved more useful to Geoffrey than to his wife. During a rapid campaign the conquest of the duchy had at last been really begun, and in the two following years it was carried to a successful conclusion. On January 20,1144, the city of Rouen surrendered to the Count of Anjou, though the castle held out for some time longer. Even Waleran of Meulan recognized the new situation of affairs, and gave his aid to the cause of Anjou, and before the close of the year Louis VII formally invested Geoffrey with the duchy. This much of the plan of Henry I was now realized; Stephen never recovered possession of Normandy. But without England, it was realized in a way which destroyed the plan itself, and England was still far from any union with the Angevin dominions.