Joan was the eldest child of King
Charles III of Navarre and his wife
Eleanor, daughter of King
Henry II of Castile. Her younger sisters were
Blanche,
Beatrice, and
Isabella. Joan was originally betrothed in 1401 to
Martin I of Sicily, the heir to the throne of
Aragón. He was widower of
Maria of Sicily, who had not given him surviving children. Plans were however changed and Martin married Joan's sister Blanche. Joan herself married at
Olite on 12 November 1402 to
John, Viscount of Castellbò, the heir to the
County of Foix in France. The couple were married for eleven years but failed to produce any children. A month after her wedding, Joan was recognized as
heiress presumptive to the throne of Navarre at Olite on 3 December 1402. There the
Estates of Navarre swore an oath to Joan and John as their future sovereigns. This was after the early death of Joan's only brothers, Charles and Louis, in quick succession earlier in the year. In 1404, Joan contracted
smallpox and was treated by the Jewish doctor Abraham Comineto. During her regency she had her own personal salaried doctor, Salomon Gotheynno, also a Jew. Joan governed Navarre in the name of her father while he was in Paris between 1409 and 1411. In 1412 she became
Countess of Foix when her husband succeeded his father in the county. She died in the
Principality of Béarn in July 1413, childless. Her younger sister Blanche became heiress presumptive to the throne of Navarre, and succeeded their father Charles III on 8 September 1425. ==References==