 In 1275, Violant's son and heir to Castile, Ferdinand de la Cerda died heir to the Castilian-Leonese throne and Alfonso at first ignored the rights of Ferdinand's two sons, Alfonso and Fernando, and instead made their second son, Prince Sancho heir; he would later succeed as Sancho IV of Castile.In response, the widow of Ferdinand, Blanche of France, enlisted the help of her brother, Philip III of France.At the same time, queen Violant sought support for her grandchildren from her brother, King Peter III of Aragon, who agreed to protect and guard them in the kingdom of Aragon, accommodating her grandchildren in the Castle of Xativa.