John was born in 1316 at Eltham Palace, Kent. On 6 October 1328, at the age of twelve, he was created Earl of Cornwall. Caught in the throes of the war between his father, Edward II, and his mother, Isabella, his growing years were turbulent. He was passed between his parents and was even held in the Tower of London for a time before his brother, Edward III, led a coup against their mother and assumed his majority. Information on John is scant, but by most historical accounts he was highly competent, and highly trusted by Edward. He was named "Guardian of the Realm" when Edward III was out of the country, was asked to open Parliament in Edward's absence, and was named Warden of the northern Marches, which gave him virtual autonomy in that portion of England. As the younger brother of the English monarch, since early childhood marital negotiations were made for John: in March 1328 Edward III entered into negotiations for a marriage between his brother and María Díaz de Haro, heiress of the Lordship of Biscay, and in December 1335 were made negotiations for a wedding with Joan, Countess of Penthièvre and heiress of the Duchy of Brittany; however, it doesn't seem that any of these arrangements resulted in an official betrothal. At the end, by contract signed on 28 September 1334, John was betrothed with Maria de La Cerda, Lady of Lunel and daughter of Ferdinand de la Cerda by his wife Juana Núñez de Lara, Lady of Lara. A dispensation was sought, but the contract was abandoned when relations between Edward and Philippe worsened in late 1334. Marie married Charles d'Évreux at Poissy in April 1335 At seventeen he was a key commander in the Battle of Halidon Hill, a devastating defeat for the Scots. Later he commanded an army in the southwest of Scotland that put down resistance to Edward Balliol, whose claims to the Scottish throne were supported by England. According to Scottish accounts, who view John as a ruthless destroyer, he burned down Lesmahagow Abbey when it was filled with people who had sought sanctuary from the wrath of the English troops. As the Scottish chronicler John of Fordun tells it, this violation of the sacred laws of sanctuary so enraged King Edward III that he killed his own brother in fury. According to modern historian Tom Beaumont James, this tale "challenges the distinction between history and story." John died at Perth, probably from a fever, shortly after turning 20. In January 1337, Edward buried his brother with all honours in a beautiful alabaster-carved tomb in Westminster Abbey, and regularly had masses said for his soul.
