As a result of the Treaty of Tarbes signed on 10 May 1399, John's parents were given possession of the County of Foix, but it required that his father renounce his English alliance, and it stipulated that John and one of his brothers were to be sent as hostages to the Royal Court of France to ensure observance of the terms of the treaty. On 24 April 1406 Charles VI of France recognised John as heir to the County of Foix and he was also involved in several operations against the English: the Siege of Bordeaux in 1404-1405 and the Seat of Blaye in 1406. In 1409, John accompanied King Martin of Aragon on an expedition to Sardinia against the Genoese at the Battle of Sanluri on 30 May 1409 and returned to Foix in September.
When Martin died on 31 May 1410 without surviving children, two princes tried to claim the succession: Ferdinand of Castile, nephew of Martin and Louis II of Anjou, married to Yolande of Aragon, daughter of King John I of Aragon, brother and predecessor of Martin. The dowager QueenViolant of Aragon, widow of King John I, wrote to John on 20 January 1411 promising the return of Rosanes and Martorell if her daughter Yolande succeeded to the throne, as a result John sent troops to help Louis and Yolande in their claim, but Ferdinand prevailed ultimately on 25 June 1412 by the compromise of Caspe. However, John was able to gain the lost estates by a marriage to Joanna of Urgell, granddaughter of Peter IV of Aragon. John fought with Aragon against Castile, but helped his brother Peter, Cardinal of Foix and Arles, to crush insurgents from Aragon.
Count of Foix
John's father Archambaud died in 1412, John then became Count of Foix; he was co-ruler of Foix with his mother Isabella until her death in 1428. In 1402, John married Joan, eldest daughter of Charles III of Navarre; two monthsafter the wedding, she was formally recognised as heiress presumptive of Navarre. Navarre would have become part of the Foix inheritance if John and Joan had children, but they failed to produce children and Joan died in July 1413. During the Hundred Years War, John switched his support between the English and French a few times, mainly for his own personal gain; always aligning with the side who promised him the most political and economic benefits at the relevant time. As sovereign of the Pyrenean Principality he took up a neutral stance in the war which was reflected in its motto ni Anglais, ni Français. John became Count of Bigorre in 1415 by agreement with Bernard VII, Count of Armagnac, the title was finally recognised by the King of France by letters dating from 18 November 1425, which definitively stabilized John's new position. The King of France installed him as Governor of Dauphiné in 1416. In 1425 he was appointed Governor of Languedoc and received from the King the title Viscount of Lautrec. He also bought the Viscountcy of Villemur. Although John was sided with the French at the time, he did not take part in the Battle of Agincourt; the French army suffered a crushing defeat by the English forces commanded by King Henry V. John's brother Archambaud was killed during the battle. John died 4 May 1446 and was succeeded by his son Gaston.
Family
John married firstly to Joan of Navarre in 1402; they had no children. John married secondly in 1422 to Jeanne d'Albret. She was the daughter of Charles I of Albret, co-commander of the French Army in the Battle of Agincourt where in 1415 he was killed. John and Jeanne had two children:
After Jeanne's death, John married thirdly in 1436 to Joanna, daughter of James II of Urgell and Isabella of Aragon; they had no children, but the marriage helped John recover the remaining Spanish property he was owed. John had four children by unknown mistresses:
Isabella married 11 May 1443 to Bernard, Baron de Cauna and had issue
Bernard, Seigneur de Gerderest married Praxede de Caramany
