Oxford Parliament (1258)

The Oxford Parliament (1258), also known as the "Mad Parliament" and the "First English Parliament", assembled during the reign of Henry III of England. It was established by Simon de Montfort, 6th Earl of Leicester. The parlour or prolocutor (Speaker) was Peter de Montfort under the direction of Simon de Montfort. Simon de Montfort led the Parliament and the entire country of England for 18 months, from 1264 until his death at the Battle of Evesham.

Parliaments, sometimes as informally assembled as a "parley" would be, were scenes of negotiations between Henry and the barons, who had tasted rule by aristocracy during Henry's minority. Parliaments had been held in a series since 1246, as Henry's position weakened.

In this parliament, the great magnates' disaffection with the King reached breaking point: shortly after the Parliament adjourned, a group of barons, led by Simon de Montfort, forced King Henry to accept a new form of government, laid out in the Provisions of Oxford, in which power was placed in the hands of a privy council, a Council of Fifteen members who were to supervise ministerial appointments, local administration and the custody of royal castles. Parliament, meanwhile, which was to meet three times a year, would monitor the performance of this council. Oaths of fealty were to be sworn to King and Council.

The Oxford Parliament of 1258 was preceded by Parliament of Merton of 1236 and followed by De Montfort's Parliament of 1265.