House of de la Cerda

Ferdinand de la Cerda was eldest son of King Alfonso X and heir of Castilian throne. He died before his father, and Alfonso X always stated his successor was his grandson Alfonso de la Cerda, instead of his second son, Infante Sancho. This motivated Sancho to revolt against his father. After a long civil war Sancho was finally crowned. Following an unsuccessful invasion by Aragon and Portugal, a peace settlement removed the Infante de la Cerdas from contention for the Castilian throne.