Peter and his son were removed from his counsels.  The friar’s boldness convinced him that disaffection was widespread, and he promised the magnates at a later council at London that he would, with their advice, correct whatever he found there was need to reform.  Meanwhile the Poitevins brought into England fresh swarms of hirelings from their own land, and Peter des Roches urged Henry to crush rebellion in the bud.  As a warning to greater offenders, Gilbert Basset was deprived of a manor which he had held since the reign of King John, and an attempt was made to lay violent hands upon his brother-in-law, Richard Siward.  The two barons resisted, whereupon all their estates were transferred to Peter of Rivaux.  Yet Richard Marshal still continued to hope for peace, and, after the failure of earlier councils, set off to attend another assembly fixed for August 1, at Westminster.  On his way he learnt from his sister Isabella, the wife of Richard of Cornwall, that Peter des Roches was laying a trap for him.  In high indignation he took horse for his Welsh estates, and prepared for rebellion.

The king summoned the military tenants to appear with horses and arms at Gloucester on the 14th.  There Richard Marshal was declared a traitor and an invasion of his estates was ordered.  But the king had not sufficient resources to carry out his threats, and October saw the barons once more wrangling with Henry at Westminster, and claiming that the marshal should be tried by his peers.  Peter of Winchester declared that there were no peers in England as there were in France, and that in consequence the king had power to condemn any disloyal subject through his justices.  This daringly unconstitutional doctrine provoked a renewed outcry.  The bishops joined the secular magnates, and threatened their colleague with excommunication.  A formidable civil war broke out.  Siward and Basset harried the lands of the Poitevins, while the marshal made a close alliance with Llewelyn of Wales.  The king still had formidable forces on his side.  Richard of Cornwall was persuaded by Bishop Peter to take up arms for his brother, and the two new earls, John the Scot of Chester, and John de Lacy of Lincoln, joined the royal forces.  Hubert de Burgh took advantage of the increasing confusion to escape from Devizes castle to a church in the town.  Dragged back with violence to his prison, he was again, as at Brentwood, restored to sanctuary through the exertions of the bishop of the diocese.  There he remained, closely watched by his foes, until October 30, when Siward and Basset drove away the guard, and took him off with them to the marshal’s castle of Chepstow.