Ferdinand predeceased his father in 1275 at Ciudad Real. Blanche and Ferdinand's sons did not inherit the throne of their grandfather, since their uncle, the second son, Sancho, enforced his claim, even by rebelling. Blanche's brother Philip warned Sancho that he would invade Castile on behalf of his two nephews.
Blanche left Castile never to return. Her sons were sent to live with their grandmother Violant of Aragon who had them sent to the fortress of Xàtiva so they would be safe from Sancho.