Henry IV of Castile

Henry IV of Castile
January 5, 1425 – December 11, 1474

Henry IV of Castile was born on January 25, 1425, in Valladolid, Castile. The son of King John II and Queen Maria of Aragon, the prince would outlive his three siblings. During Henry’s childhood, John experienced a rough reign and struggled as a ruler. Weak-willed and politically incompetent, John relied heavily on his favorite advisor, Alvaro de Luna. Although a capable politician, de Luna’s lack of wealth caused him to use his position to acquire many estates and funds. As a result, his greed made him unpopular in Castile.

To maintain his influence, Alvaro de Luna gave Prince Henry a separate court. Although de Luna did this to control Henry, the prince became influenced by the advisor’s enemies. After the death of Queen Maria on September 4, 1458, the widowed John II sought a new wife. In 1447, the 42-year-old king married 19-year-old Isabella of Portugal. Unlike her predecessor, Isabella actively sought the downfall of Alvaro de Luna. Facing pressure from his wife and son, John reluctantly ordered his advisor’s execution in June 1453.

King of Castile

Upon de Luna’s death, Isabella dominated the king during the last years of his reign. On July 20, 1454, John II died from natural causes. Besides Prince Henry, the king left behind two children by Isabella: Isabella (b. 1451) and Alfonso (b. 1453). The following day after his father’s death, the prince became King Henry IV of Castile. The new king inherited a weak monarchy and sought to strengthen his position.

Although already married, Henry IV wanted an annulment from Blanche II of Navarre. Claiming to be cursed with impotence with Blanche, Pope Nicholas V agreed, and the marriage was annulled in 1453. Now a newly single man, the king arranged a marriage with Portugal. As part of the alliance, Henry married Afonso V‘s sister, Joan of Portugal. Aware of his weak position, the king viewed his younger half-siblings as possible threats to his throne. Although initially sent away, Henry recalled Isabella to court and kept her as a virtual prisoner.

As Henry IV’s reign progressed into the early 1460s, the king demonstrated the same political incompetence as his father. Easily influenced, the king allowed his advisors to run the government on his behalf. In turn, infighting amongst the king’s favorites allowed lawlessness and instability to increase in Castile. As royal authority broke down, the nobility took power into their own hands. When the king finally had an heir, Joanna, in February 1462, the Castilian nobility believed her to be the daughter of one of Henry’s advisors, Beltran de la Cueva. Although doubtful, Henry eventually divorced Joan in 1468 after discovering her affair with a bishop’s nephew.

Civil War

Believing Princess Joanna to be illegitimate, the Castilian nobility viewed Alfonso as his brother’s rightful heir. Pressured by the nobility, Henry IV agreed to disinherit Joanna in favor of Alfonso. However, the king quickly broke his promise. Over the next several years, Henry fought against his brother in a civil war. The war only concluded due to the death of Alfonso on July 4, 1468. Despite the loss of the prince, the nobility quickly threw their support behind Princess Isabella.

Isabella I of Castile
Princess Isabella

Recognizing her situation, the politically savvy Isabella sought to make peace with her brother. In September, both siblings agreed to the Accord of Toros de Guisando. In exchange for becoming Henry IV’s heir, the king would choose her husband. Henry wanted Isabella to marry King Afonso V of Portugal, but the princess had another suitor in mind. Sneaking away from court in October 1469, Isabella secretly married Prince Ferdinand of Aragon instead.

Final Years

Enraged at his sister’s betrayal, Henry IV refused to honor his end of the Accord. Once more, Princess Joanna became the king’s heir, and he began arranging her marriage. As the king’s health declined in 1474, Henry asked Afonso V to marry his daughter. The king hoped that Afonso would have the military might to secure Castile’s throne for him and Joanna. The Portuguese king agreed, and Henry died on December 11, 1474.


Henry IV of Castile would be the last of a line of weak Castilian kings. During his reign, Henry proved to be an inept ruler that allowed others to rule on his behalf. In turn, his kingdom descended into lawlessness and chaos as royal advisors fought amongst themselves. As the monarchy’s authority declined, the nobility’s power increased. By ignoring the nobility’s growing power, Henry allowed them an opportunity to threaten his throne, beginning a civil war. The king’s final actions before his death set the stage for another civil war between his daughter and half-sister.


Dougherty, M. J. (2018). Kings & Queens of the Medieval World: From Conquerors and Exiles to Madmen and Saints (pp. 76-78). London: Amber Books.

Encyclopædia Britannica, inc. (n.d.). Henry IV. Encyclopædia Britannica. Retrieved January 18, 2022, from https://www.britannica.com/biography/Henry-IV-king-of-Castile


Andy Tree

I'm a European history enthusiast who seeks to share his passion with others. I hope to inform and inspire readers with my posts!


  1. Thank you! I am watching a series about Queen Isabel (in Spanish, which makes it much harder for me to follow) and the information you present on Henry IV was very helpful for me to understand better. I am going to search to see if you have a post on Isabella and/or her brother Alfonso.

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