1447 he bought the viscounty of Narbonne, and having assisted King Charles VII in Guyenne, he was made a peer of France in 1458. In 1455 his father-in-law designated him as his successor in Navarre, and Louis XI of France gave him the counties of Roussillon and Cerdagne, and made him his representative in Languedoc and Guyenne; but these marks of favor did not prevent him from joining a league against Louis in 1471. His eldest son, Gaston, the husband of Madeleine, a daughter of Charles VII of France, died in 1470, and when Gaston IV died two years later, his lands descended to his grandson, Francis Phoebus (died 1483). Francis Phoebus became king of Navarre in 1479 and was succeeded by his sister Catherine (died 1517), the wife of Jean d'Albret (d. 1516). A younger son of Count Gaston IV was John (died 1500), who received the viscounty of Narbonne from his father and married Marie, a sister of the French king Louis XII. He was on good terms both with Louis XI and Louis XII, and on the death of his nephew Francis Phoebus in 1483, claimed the kingdom of Navarre against Jean d'Albret and his wife, Catherine de Foix. The ensuing struggle lasted until 1497 when John renounced his claim. He left a son, Gaston de Foix (1489–1512), a distinguished French general, and a daughter, Germaine de Foix, who became the second wife of Ferdinand II of Aragon. In 1507, Gaston exchanged his viscounty of Narbonne with King Louis XII of France for the duchy of Nemours, and as duke of Nemours he took command of the French troops in Italy. After delivering Bologna and taking Brescia, Gaston encountered the troops of the Holy League at Ravenna in April 1512 and routed the enemy, but was killed during the pursuit. There were also younger branches of the house of Foix-Grailly: the viscounts of Lautrec (descended from Pierre de Foix, younger son of Jean III); the Counts of Candale and Benauges (descended from Gaston de Foix, a younger son of Archemboult and his son John de Foix, 1st Earl of Kendal); the Counts of Gurson and Fleix and Viscounts of Meille (Jean de Foix, Comte de Meille, Gurson et Fleix, was a younger son of Jean de Foix, Earl of Kendal), and the Counts of Caraman, or Carmain, descended from Isabeau de Foix, Dame de Navailles (only child