Henry IV of Castile

He was the son of John II of Castile and Maria of Aragon, daughter of King Ferdinand I of Aragon. He displaced his older sister, Eleanor, and became heir apparent to the Castilian throne as the Prince of Asturias.

At the time of his birth, Castile was under control of Álvaro de Luna, Duke of Trujillo, who intended to select Henry's companions and direct his education. The companions of his own age included Juan Pacheco, who became his closest confidant. The struggles, reconciliations and intrigues for power among the aristocracy, Álvaro de Luna, and the Infantes of Aragon would be constant. Read Less

Six years after the birth of the throne's heir, part of the nobility of Castile revolted against the king. The rebels claimed that the princess was not the daughter of the king, but actually the daughter of Beltrán de La Cueva, 1st Duke of Alburquerque. This hypothesis was reinforced when the Queen had another two children with the nephew of a Bishop. Though many contemporary historians and chroniclers assumed Henry was impotent, the royal chronicles of his reign were all written or revised during the reign (and under the influence) of Isabella I, his half-sister and ultimate successor, whose strong interest in proving Joan illegitimate renders these accounts at least partially suspect. The question of Joan's paternity is therefore not firmly answerable, given the lack of available reliable sources.

The doubt of her legitimacy as an heir, the weakness of the king, the adultery of the queen, and the unruliness of the nobility all set the stage for a struggle for succession after Henry's death. Henry divorced his wife after her scandalous behavior with Bishop Fonseca's nephew. After a long period of conflict between the rival factions, Henry finally agreed to name Isabella his successor, in Guisando (Avila), provided she allow him to arrange her strategic marriage. Isabella would go on to break this stipulation of the agreement. Read Less