John Cornwall, 1st Baron Fanhope and Milbroke, KG, PC (c. 1364 – 11 December 1443; also spelled Cornewall, Cornwaille, Cornouayl), was an English nobleman and soldier and one of the most respected chivalric figures of his era.

Sir John was deeply affected by witnessing the death of his son and heir, and vowed never to wage war on Christian princes.

[3] The couple's daughter was Constance Cornwall, who married John FitzAlan, 14th Earl of Arundel, and died in 1427.

During the Middle Ages, tournaments were regarded as the greatest test of a warrior's skill and valour; an idea reinforced by the prominent place that it occupied in popular Arthurian lore of the era.

However, he came into conflict with Henry V when his 17-year-old son, also named John, "a fine and valiant squire",[4] was killed during the siege of Meaux; the elder Cornwall was heard to bellow that Henry's war was proceeding "contrary to God and reason",[4] and immediately departed for England, apparently swearing an oath never to fight again.

He profited greatly from the ransoms of prisoners, and used the spoils to build Ampthill Castle, Bedfordshire, and to buy Oyster Hill Manor from the Mayor of London, William Walworth.

The Church of St Andrew in Ampthill has Sir John and Elizabeth of Lancaster immortalized in stained glass windows.

[7] Sir John features as a loquacious and plain-talking leadership character in Bernard Cornwell's novel Azincourt (U.S. title, Agincourt).