Earl of Warwick, of Elmley and Salwarpe, Worcestershire. Hereditary Sheriff of Worcestershire and hereditary Pantler (in charge of the bread and pantry) at the King Richard's coronation.
Son of William de Beauchamp and Isabel Mauduit, grandson of Walter de Beauchamp and Joane de Mortimer, William Mauduit and Alice de Beaumont.
William married Maud FitzJohn, as her second husband, the daughter of John FitzGeoffrey and Isabel le Bigod. They were married before 1270 and had one son and three daughters:
Sir Guy, Earl of Warwick
Isabel, wife of Sir Patrick Chaworth and Hugh le Despenser
Anne, nun at Shouldham
Amy, nun at Shouldham
William was heir to his uncle, William Mauduit, by which he inherited the Earldom of Warwick in 1268, as well as the office of the Chamberlain of the Exchequer, the baronies of Warwick and Hanslope in Buckinghamshire.
William was a close friend of King Edward I, and an important military leader in Edward's invasion into Wales in 1277, raised the siege of Conwy Castle in 1294, where the King had been penned in, defeated the Welsh at Maes Moydog in March 1295 against the Prince of Wales, Madog ap Llywelyn. In a night attack on the Welsh infantry, he used cavalry to drive them into compact formations, which were then shot up by his archers, and charged.
William defeated the Scots at Dunbar 27 April 1296 and was with the English at the defeat of Sterling in 1297. He was described as a "vigorous and innovative military commander".
By his wife, he inherited the manors of Cherhill, Wiltshire, Potterspury, Northamptonshire, Quarrendon, Buckinghamshire and a cantread (district) of townships in the Isles of Thomond in Ireland. William received a licence to crenellate Hanslope 10 June 1292.
William died at Elmley on the 5th or 9th of June, 1298, Maud died in April 1301 and they both were buried at Friars Minor (Greyfriars) at Worcester.
Maud FitzJohn Beauchamp