Isabella was firstly betrothed to
Infante John of Aragon around 1414. Her mother, Queen Eleanor bequeathed her money for the marriage. John later became
King of Aragon but broke off his contract with Isabella, in hopes of marrying
Joanna II of Naples. Isabella eventually married on 10 May 1419
John IV of Armagnac. This marriage was John's second marriage, after the death of his first wife Blanche of Brittany, who had left no sons. Isabella and John had five children: •
Marie of Armagnac (b. 1420–1473), married in 1437
John II of Alençon (b. 1409–1476),
Duke of Alençon; maternal great-grandparents of King
Henry IV of France. •
John V of Armagnac (b. 1420–1473), Viscount of Lomagne, then Count d' Armagnac, of Fézensac and Rodez. He married illegally to younger sister Isabella, had issue and married secondly to Joan of Foix, also with issue. • Eleanor (b. 1423–1456), married in 1446
Louis de Chalon (b. 1389; † 1463), Prince d'Orange, Lord of Arlay and Arguel, had issue •
Charles I (b. 1425–1497), Viscount of Fézensaguet, then Count d' Armagnac, of Fézensac and Rodez • Isabella (b. 1430–1476), Lady of the Four-Valleys, married illegally to brother John and had issue. Isabella and her husband both died in 1450; she died in August and he died three months later in November, she was around fifty-four at the time of death. ==Ancestry==