This became outright hostility in 1207 when John began to move against several major Irish magnates, including William. Though he left for Leinster in 1207 William was recalled and humiliated at court in the autumn of 1208, while John's justiciar in Ireland Meilyr fitz Henry invaded his lands, burning the town of New Ross. Meilyr's defeat by Countess Isabel led to her husband's return to Leinster. He was once again in conflict with King John in his war with the Braose and Lacy families in 1210, but managed to survive. He stayed in Ireland until 1213, during which time he had Carlow Castle erected and restructured his honour of Leinster. Taken back into favour in 1212, he was summoned in 1213 to return to the English court. Despite their differences, William remained loyal throughout the hostilities between John and his barons which culminated on 15 June 1215 at Runnymede with the sealing of Magna Carta. William was one of the few English earls to remain loyal to the king through the First Barons' War. It was William whom King John trusted on his deathbed to make sure John's nine-year-old son Henry would get the throne. It was William who took responsibility for the king's funeral and burial at Worcester Cathedral. On 11 November 1216 at Gloucester, upon the death of King John, William Marshal was named by the king's council (the chief barons who had remained loyal to King John in the First Barons' War) to serve as protector of the nine-year-old King Henry III, and regent of the kingdom. In spite of his advanced age (around 70) he prosecuted the war against Prince Louis and the rebel barons with remarkable energy. In the battle of Lincoln he charged and fought at the head of the young King's army, leading them to victory. He was preparing to besiege Louis in London when the war was terminated by the naval victory of Hubert de Burgh in the straits of Dover. William was criticized for the generosity of the terms he accorded to Louis and the rebels in September 1217, but his desire for an expedient settlement was dictated by sound statesmanship. Self-restraint and compromise were the keynotes of Marshal's policy, hoping to secure peace and stability for his young liege. Both before and after the peace of 1217 he reissued Magna Carta, in which he is a signatory as one of the witnessing barons.