[1] The same year she was born, the greater part of Navarre was conquered by Aragon, and she was raised in France.

[2] Isabel became the godmother of her grand nephew Henry III of Navarre, whom she carried to his baptism in 1554.

Isabel came to feel sympathy for Calvinism early on, but did not convert during the lifetime of her spouse, who remained a Catholic.

In Blain, she received the Protestant reformer d'Andelot, who had a mission in Nantes and held the first Protestant sermon there with the reformers Fleurer and Loiseleur de Villiers.

In 1560, she was granted personal religious freedom for herself and her household on her own domains by the king of France.