Henry III. of England, grandson of Henry II., and eldest son of King John, was born 1st October 1207, and succeeded to the throne on his father's death at the age of nine. His reign is one of the longest and most troubled in English history, and he himself one of its least attractive and least interesting figures. The first forty-two years are for the most part a dreary record of misgovernment and purposeless extravagance, the next seven a period of strife and civil war, the remainder of little interest. Henry was more devout than his predecessors, and could boast more domestic virtues; but he inherited his father's faithlessness, and through all his impolicy exhibited a stubborn determination to be at least as autocratic as he. The interest of the reign, however, centres not in the king, but in the birth and infancy of the English constitution. In 1227 Henry declared himself of age to govern; in 1232 he deprived Hubert de Burgh, who had ruled England well as regent, and as judiciary had practically continued to govern the country, of all his offices; and in 1234 he was compelled to dismiss Hubert's rival and successor, Peter des Roches. He took the administration into his own hands, and henceforward managed everything ill both at home and abroad. A war with France cost him Poitou, and might have cost him all his continental possessions, and even his own liberty, but for the generous disposition of the French king, Louis IX. In his boyhood, under the direction of the judicious Earl of Pembroke, he re-issued the Great Charter, though with certain important omissions; and he confirmed it more than once afterwards, but always as a condition of a money grant. He was beset with favourites, chiefly from the country of his queen, Eleanor of Provence, and he allowed exorbitant exactions on the part of the pope. His misrule and extortion roused all classes, and in 1258 the parliament, as the assembly of the barons and bishops was already called, headed by his brother-in-law, Simon de Montfort, Earl of Leicester, forced him to agree to the Provisions of Oxford (q.v.), whereby he transferred his power temporarily to a commission of barons. But jealousy and disunion among the barons soon enabled Henry to repudiate his oath, and after a brief period of open war (1263) the whole matter was referred to the arbitration of Louis of France, who annulled the Provisions. De Montfort and his party disregarded their agreement to be bound by his judgment, and took up arms against the king. They defeated him, and took him prisoner in the battle of Lewes, on 14th May 1264. The battle was followed by an agreement called the Mise of Lewes (q.v.), more humiliating to the king than the Provisions of Oxford. Earl Simon now summoned the parliament (20th January 1265) which has since been famous as the first assembly of the sort in which boroughs were represented; although it was nearly the end of the century before the representatives of towns began regularly to sit in parliament. De Montfort's supremacy did not last long. Within a year the powerful Earl of Gloucester deserted his party, and, with Prince Edward, who had escaped from captivity, led an overwhelming army against him. Simon was defeated and slain at Evesham, on 4th August 1265. With this event the importance of this long, dismal reign ends. Henry died on 16th November 1272, and his son Edward, though absent in Palestine, was at once proclaimed king.
See Freeman, Stubbs (vol. ii.), Prothero's Life and Times of Simon de Montfort (1887), and other works cited at MONTFORT.