It was over this Sicilian scheme, the crowning folly of the king, that public opinion at last grew so hot that the intermittent criticism and grumbling of the baronage and the nation passed into vigorous and masterful action. At the Mad Parliament, which met at Oxford, 1258, the barons informed their master that his misgovernment had grown so hopeless that they were resolved to put him under constitutional restraints. They appointed a committee of twenty-four, in which Simon de Montfort was the leading spirit, and entrusted it with the duty, not only of formulating lists of grievances, but of seeing that they were redressed. Henry found that he had practically no supporters save his unpopular foreign relatives and favourites, and yielded perforce.
To keep him in bounds the celebrated Provisions of Oxford were framed. They provided that he was to do nothing without the consent of a permanent council of fifteen barons and bishops, and that all his finances were to be controlled by another committee of twenty-four persons. All aliens were to be expelled from the realm, and even the king's household was to be reformed by his self-constituted guardians. The inevitable oath to observe honestly all the conditions of the Great Charter of 1215 was, as usual, extorted from him with special formalities. Though Montfort and the barons voiced the public discontent, the constitution which they thus imposed on the king had nothing popular about it. The royal functions of which Henry was stripped were to be exercised by a series of baronial committees. The arrangement was too cumbersome, for there was nothing which would be called a central executive; the three bodies (two of twenty-four members each, the third of fifteen) were interdependent, and none of them possessed efficient control over the others. It was small wonder that the constitution established by the Provisions of Oxford was found unworkable. They were not even popular; the small landholders and subtenants discovered that their interests had not been sufficiently regarded, and lent themselves to an agitation against the provisional government, which was got up by Edward, the king's eldest son, who now appeared prominently in history for the first time. To conciliate them the barons allowed the Provisions of Westminster to be enacted in 1259, in which the power of feudal courts was considerably restricted, and many classes of suit were transferred to the royal tribunals, a sufficient proof that the king's judges did not share in the odium which appertained to their master, and were regarded as honest and impartial.
The limited monarchy established by the Provisions of Oxford lasted only three years. Seeing the barons quarrelling among themselves, and Montfort accused of ambition and overweening masterfulness by many of his colleagues, the king took heart. Copying the example of his father in 1215, he obtained from the pope a bull, which declared the new constitution irregular and illegal, and absolved him from his oath to abide by it. He then began to recall his foreign friends and relatives, and to assemble mercenaries. De Montfort answered by raising an army, arresting prominent aliens, and seizing the lands which the king had given them. Henry thereupon, finding his forces too weak to face the earl, took refuge in the Tower of London and proposed an arbitration. He offered to submit his case to Louis IX, the saintly king of France, whose virtues were known and respected all over Europe, if the baronial party would do the same.
An appeal to the pope they would have laughed to scorn; but the confidence felt in the probity of the French king was so great that Montfort advised his friends to accede to the proposal. This was an unwise step. Louis was a saint, but he was also an autocratic king, and had no knowledge of the constitutional customs of England. Having heard the claims of the king and the barons, he issued the Mise of Amiens (January 23, 1264), so called from the city at which be dated it, a document which stated that King Henry ought to abide by the terms of Magna Carta, to which he had so often given his assent, but that the Provisions of Oxford were wholly invalid and derogatory to the royal dignity. We ordain, he wrote, that the king shall have full power and free jurisdiction over his realm, as in the days before the said Provisions. The pope shortly afterwards confirmed the French king's award.
Simon de Montfort and his friends were put in an awkward position by this decision, to which they had so unwisely committed themselves. But they did not hesitate to declare that they must repudiate the mise. Simon declared that it would be a worse perjury to abandon his oath to keep the Provisions of Oxford than his oath to abide by the French king's award. He took arms again at the head of the Londoners and his personal adherents and allies. But many of the barons stood neutral, not seeing how they could refuse to accept the arbitration they had courted, while a number not inconsiderable joined the king, deciding that Leicester had passed the limits of reasonable loyalty, and that their first duty was to the crown.
Text extracted from the entry for ENGLISH HISTORY in the 1911 Encyclopedia Britannica, the text of which lies within the public domain.