High Quality Content by WIKIPEDIA articles! The Mise of Amiens was a settlement given by King Louis IX of France on 23 January 1264 in the conflict between King Henry III of England and his rebellious barons, led by Simon de Montfort. Louis` one-sided decision for King Henry led directly to the hostilities of the Barons` War. The conflict between king and magnates was caused by dissatisfaction with the influence of foreigners at court, and Henry`s high level of taxation. In 1258 Henry was forced to accept the Provisions of Oxford, that essentially left royal government in the hands of a council of magnates, but this document went through a long series of revocations and reinstatements. In 1263, as the country was on the brink of civil war, the two parties agreed to submit the matter to arbitration by the French king. Louis was a firm believer in the royal prerogative, and decided clearly in favour of Henry.