Juan Manuel, Prince of Villena
In April 1311, while in Palencia, Ferdinand IV became gravely ill and was transported to Valladolid, despite the protests of Constance, who wished his transport to Carrión de los Condes, with the purpose to control him with the help of her ally, Juan Núñez II de Lara. During the King's illness, disputes erupted between Juan Núñez II de Lara, Ferdinand IV's brothers and Juan Manuel, Prince of Villena. While the King was in Toro, the Queen gave birth in Salamanca on 13 August 1311 a son, the future Alfonso XI of Castile. The newborn heir to the Castilian throne was baptized in the Old Cathedral of Salamanca, and, against the King's wishes (who wanted to trust his son to his mother María de Molina), the will of Constance prevailed, who (with the support of Juan Núñez II de Lara and Lope Díaz de Haro) wanted to give the custody of the prince to Peter, Lord of Cameros and brother of Ferdinand IV.