Robert D'Oyly the younger, Robert D'Oyly the elder's nephew, had inherited the castle by the time of the civil war of the Anarchy in the 1140s.[1] After initially supporting King Stephen, Robert declared his support for Empress Matilda, Stephen's cousin and rival for the throne, and in 1141 the Empress marched to Oxford to base her campaign at the castle.[28] Stephen responded by marching from Bristol in the Autumn of 1142, attacking and seizing the town of Oxford and besieging Matilda in the castle.[3] Stephen set up two siege mounds beside the castle, called Jew's Mount and Mount Pelham, on which he placed siege engines, largely for show, and proceeded to wait for Matilda's supplies to run low over the next three months.[4] Stephen would have had difficulty in supplying his men through the winter period, and this decision shows the apparent strength of Oxford Castle at the time.[29]