Richard Marshal came to the fore as the leader of the baronial party, and the chief antagonist of the foreign friends of King Henry III of England, notably Peter de Rivaux. Fearing their treachery, he refused to visit King Henry III at Gloucester in August 1233, and King Henry declared him a traitor.

Hostilities followed, and Richard made an alliance with the Welsh Llywelyn the Great. He crossed from Wales to Ireland, where Peter des Roches had instigated his enemies to attack him, and in April 1234 he was overpowered and wounded, and died a prisoner. He was succeeded by another of his brothers, Gilbert.