John I, Count of Foix also known as Jean de Foix-Grailly (1382 – 4 May 1436) was Count of Foix from 1428 until his death in 1436. He succeeded his mother Isabella, Countess of Foix. His father was Archambaud de Grailly. Life Early life 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. Aragon 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 Queen Violant of Aragon, widow of King John I, wrote to John on 20 January 1411 promising the return of Rosanes and Martorell (part of the properties confiscated from his maternal uncle Matthew of Foix) 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 months after the wedding, she was formally recognised as heiress presumptive of Navarre. Navarre would have become