Henry III reigned fifty-six years (1216–1272), rebuilt Westminster Abbey and the ideology of sacral kingship, and provoked the baronial revolution of 1258–1265 that forced parliament into English government.
Crowned at nine with a French prince holding London, Henry III owed his throne to William Marshal's regency and the reissued Magna Carta. His long personal rule was pious, artistic, extravagant, and politically maladroit: foreign favourites, failed continental schemes, and the ruinous "Sicilian business" drove the baronage under Simon de Montfort to impose conciliar government in 1258.
The Barons' War that followed saw the king captured at Lewes in 1264 and rescued by his son Edward's victory at Evesham in 1265. His truest monument is Westminster Abbey, rebuilt at staggering cost around the shrine of Edward the Confessor.
Henry was born at Winchester in 1207 and inherited, at nine, a kingdom half-occupied by the French prince Louis and the rebel barons. The old regent William Marshal won the war for him — Lincoln by land, Sandwich by sea — and won the peace by reissuing Magna Carta in the young king's name, turning the rebels' manifesto into the crown's own promise.
The minority government of Marshal, the legate, and Hubert de Burgh rebuilt royal authority castle by castle. Henry emerged into full power in 1227 with a high sacral notion of kingship — and none of the military or managerial instincts of his grandfather Henry II.
Contemporaries found Henry easy to describe and hard to respect. Matthew Paris, who knew and constantly criticised him, shows a king devout to the point of ostentation — hearing Mass daily, feeding hundreds of paupers, obsessed with the cult of Edward the Confessor — and simultaneously petulant, credulous, and changeable, "simplex" in the chronicler's damning word. He wept easily, forgave easily, and made the same mistakes serially.
His genuine gifts were aesthetic. The rebuilding of Westminster Abbey, the patronage of goldsmiths and painters, the elaboration of court ceremony — these came from real discernment and made his court the artistic centre of the realm. Dante would later place him, gently, in purgatory as the "king of simple life"; his own barons put it more brutally when they insisted he govern through a council, since he would not be governed by judgment.
Henry's continental ambitions ran backwards: expeditions to recover Poitou failed at Taillebourg in 1242, and by the treaty of Paris (1259) he formally surrendered Normandy, Anjou, and Poitou, keeping Gascony as a French fief. The "Sicilian business" — accepting the pope's offer of the Sicilian crown for his son Edmund in exchange for underwriting a papal war — saddled the crown with impossible debts and triggered the explosion.
In 1258 a coalition of magnates led by Simon de Montfort forced the Provisions of Oxford on him: a council of fifteen chosen with the barons, thrice-yearly parliaments, and reforming justices in the shires. Henry's repudiations and the barons' divisions slid into war; Montfort captured king and heir at Lewes in May 1264 and ruled through the famous parliament of 1265 that first summoned burgesses alongside knights. Edward's escape and victory at Evesham in August 1265, where Montfort was killed and dismembered, restored the king — but the Dictum of Kenilworth and the statute of Marlborough conceded much of the reform in the crown's own name.
Henry's final years were quiet, spent finishing the abbey; the Confessor's relics were translated into their new shrine in October 1269 with the king and his sons carrying the coffin. He died at Westminster on 16 November 1272, with Edward away on crusade.
So secure was the settlement after Evesham that the succession passed without a ripple to an absent heir — the first time since 1066 that England changed kings with the successor overseas and no one under arms.
The constitutional residue of Henry's misgovernment proved permanent: regular parliaments, the community of the realm as a political actor, and the principle — extracted, resisted, and finally absorbed — that the king rules with counsel. Edward I built his stronger monarchy on exactly those foundations.
Westminster Abbey as it stands is substantially Henry's building, and the coronation church he made around the Confessor's shrine has crowned every monarch since. No English king left a greater work of art; few left a thinner record of political judgment.