In 1427, she, her brother Charles, and her sister Eleanor were proclaimed the rightful heirs of the kingdom of Navarre. Blanche was promised to the heir of Castile in the peace treaty between Navarre and Castile in 1436. She married Henry, Prince of Asturias (later King Henry IV of Castile) in 1440. The marriage was reputedly never consummated.
In 1453, after thirteen years, Henry sought the annulment of the marriage. An official examination confirmed the virginity of Blanche. A divorce was granted by the Pope on the grounds that some "witchcraft" had prevented Henry from consummating the marriage. After this, Blanche was sent home to Navarre, where she was imprisoned by her family: from 1462, she was under the custody of her sister. She remained childless throughout her life.
Claimant to the throne
After the death of her brother in 1461, some dissatisfied Navarrese elements and some of the anti-Aragonese party regarded Blanche as the rightful monarch, as they had regarded Charles. They proclaimed her queen. She would have thus become Blanche II of Navarre, had not her father (who wanted to keep the government of Navarre) already had her incarcerated and thus not capable to act.
John tried to marry her to Charles, Duke of Berry, and younger brother of Louis XI of France to make an alliance, but Blanche refused, and her act irritated her father. In 1464, she came back to Pamplona with the help of its bishop Nicolas de Etchabarri, who was murdered shortly after, in order to attend the Courts of Navarre.[1]
She died by poison in Orthez less than a month later. Both her father and her sister Eleanor are suggested to have been responsible for her death. Upon her death, her rights to Navarre were inherited by her next sister, Eleanor of Aragon, Countess of Foix, who however was their father's ally and supporter, and did not press her own claims until his death in 1479.