When the Great Council system of consultation and consent broke down, it often became impossible for government to function effectively. The most prominent instances of this, before the reign of Henry III, are the disagreements between Thomas Becket and Henry II and between King John and the barons. Becket, who served as Archbishop of Canterbury between 1162 and 1170, was murdered after a long running dispute with Henry II over the jurisdiction of the Church. John, who was king from 1199 to 1216, aroused such hostility from many leading noblemen that they forced him to agree to Magna Carta in 1215. King John's refusal to adhere to this charter led to civil war.