Ferdinand IV of Castile

Ferdinand IV, called the Summoned (1285–1312), became king of Castile and León in 1295, aged nine. His mother María de Molina held the regency, defending his throne against revolts led by his uncle John of Castile and other nobles. The Pope legitimized him in 1301, when he came of age.

In 1302 he married Constance of Portugal. Continuing the Reconquista, he failed before Algeciras in 1309 but captured Gibraltar that year and took Alcaudete in 1312.

In 1312 he promoted judicial reform to strengthen royal authority. He died in September 1312, aged 26, leaving the crown to his infant son Alfonso XI.