Left without legitimate sons, Gaston de Foix was easily persuaded to bequeath his lands to King Charles VI, who thus obtained Foix and Béarn when the count died at Orthez in 1391. Almost immediately after Gaston's death Charles granted the county of Foix to Matthew, Viscount of Castelbon, a descendant of Count Gaston I of Foix. When Matthew died without issue in 1398, his lands were seized by Archambault, Count of Grailly and Captal de Buch, the husband of Matthew's sister Isabella (d. 1426), who was confirmed as legitimate count of Foix in 1401.