Henry III (1 October 1207 - 16 November 1272) was the son and successor of John "Lackland" as King of England, reigning for fifty-six years from 1216 to his death. His contemporaries knew him as Henry of Winchester. He was the first child king in England since the reign of Ethelred the Unready. Despite his long reign, his personal accomplishments were slim and he was a political and military failure. England, however, prospered during his century and his greatest monument is Westminster, which he made the seat of his government and where he expanded the abbey as a shrine to Edward the Confessor. He assumed the crown under the regency of the popular William Marshal, but the England he inherited had undergone several drastic changes in the reign of his father. He spent much of his reign fighting the barons over the Magna Carta and the royal rights, and was eventually forced to call the first "parliament" in 1264. He was also unsuccessful on the Continent, where he endeavored to re-establish English control over Normandy, Anjou, and Aquitaine.