On the mound close at hand there was, after D'Oigli's day, a ten-sided keep built in the style of Henry III. To reach the mound you go within the gaol, and pass by a pathetic little row of murderers' graves, sanded heaps, distinguished by initials. Under the mound is a very deep well, covered over by a groined chamber of Transitional design. Five towers were added later to the Castle, as Agas' map (1568) shows us. After the Civil War, Colonel Draper, Governor of Oxford, "sleighted," as Wood expresses it, the work about the city, but greatly strengthened the Castle. But in the following year (1651), when the Scots invaded England, he, for some reason, "sleighted" the Castle works too. The five towers, shown in Agas' map, and other fortifications then disappeared. S. George's tower alone survives. Stern and grim that one remaining fragment of the old Castle stands up against the sky, a landmark that recalls the good government of the Norman kings. But the most romantic episode connected with it occurred amidst the horrors of the time when the weakness and misrule of Stephen, and the endeavours of Matilda to supplant him, had plunged the country into that chaos of pillage and bloodshed from which the Norman rule had hitherto preserved it. After the death of his son, Henry I. had forced the barons to swear to elect his daughter Matilda as his successor. But they elected Stephen of Blois, grandson of the Conqueror, whose chief claim to the Crown, from their point of view, was his weak character. In a Parliament at Oxford (1135) he granted a charter with large liberties to the Church, but his weakness and prodigality soon gave the barons opportunities of revolt. Released from the stern control of Henry they began to fortify their castles; in self-defence the great ministers of the late King followed their example. Stephen seized the Bishops of Salisbury and Lincoln at Oxford, and forced them to surrender their strongholds. The King's misplaced violence broke up the whole system of government, turned the clergy against him and opened the way for the revolt of the adherents of Matilda. The West was for her; London and the East supported Stephen. Victory at Lincoln placed Stephen a captive in the hands of Matilda, and the [Illustration: Oxford Castle] land received her as its "Lady." But her contemptuous refusal to allow the claims of the Londoners to enjoy their old privileges, and her determination to hold Stephen a prisoner, strengthened the hand of her opponents. They were roused to renew their efforts. Matilda was forced to flee to Oxford, and there she was besieged by Stephen, who had obtained his release.