Afonso IV of Portugal

Afonso IV of Portugal
February 8, 1291 – May 28, 1357

Afonso IV of Portugal was born on February 8, 1291, in Lisbon, Portugal. Although King Denis‘ only legitimate son, Afonso resented his father’s preference for his illegitimate son, Afonso Sanches. As Afonso aged, his resentment towards Denis turned into open hostility. The prince suspected that his father wanted to replace him with his brother. By 1320, the frustrated prince demanded that his father give him political power. When the king refused, Afonso revolted.

In May 1322, the prince’s rebellion against Denis ended. Although Queen Isabella managed to reconcile both men, the peace proved to be short-lived. Once again, Afonso started another uprising. The prince’s second revolt only ended after the king’s death on January 7, 1325. Shortly after, Afonso succeeded his father.

King of Portugal

Upon his accession as Afonso IV, the king exiled his brother, Afonso Sanches, to Castile. Afonso next consolidated his control over the Portuguese throne. After securing his kingdom, the king turned his attention towards Castile. In 1327, Afonso created a peace treaty with Alfonso XI. As part of the agreement, Alfonso married King Afonso’s daughter, Maria. However, peace only lasted between both kingdoms until 1336. Alfonso’s poor treatment of Maria angered her father, which eventually led to war.

As Afonso IV fought against Alfonso XI, a new threat emerged in the peninsula. In 1340, the Sultan of Morroco invaded Spain. Recognizing the Sultan’s threat, both men agreed to join forces. During the Battle of Rio Salado on October 30, Afonso’s actions earned him a reputation as a brave warrior. As a result, the king would achieve a great victory against the invaders.  After repulsing the Sultan’s army, Afonso maintained a friendly relationship with Castile until his death.

Civil Unrest

Once the war had ended, Afonso IV returned to Portugal to deal with internal issues. Tensions between the monarchy and nobility were high. Although the king had enjoyed the nobility’s support during his revolt against Denis, their loyalty proved weak. Portuguese nobles had grown discontent with the lack of expansion and plundering opportunities. As Afonso got older and traveled less, the king became more secluded. In response, the nobility grew more unruly.

Peter I of Portugal
Prince Peter (Peter I of Portugal)

In addition to an unhappy nobility, Afonso IV began experiencing issues with his heir, Prince Peter. Around 1340, Peter took a Galician noblewoman named Ines de Castro as his mistress. After his wife’s death, the prince openly lived with Ines and their four illegitimate children. As the prince made plans to marry his mistress, Afonso became concerned. The king feared that Ines’ relatives were trying to gain influence at court.

Afonso IV’s fears came to a head after being warned that Ines’ brother attempted to convince Peter to claim the Castilian throne. Believing that the Castros were a threat to his foreign policy, the king ordered their deaths. In January 1355, a group of assassins killed Ines. It is unknown whether or not the king directly ordered her murder. Regardless, Prince Peter revolted against his father.

Final Years

During the last two years of his life, Afonso IV focused on dealing with his son’s rebellion. On May 28, 1357, the old king died at age 66. Upon his death, Prince Peter succeeded his father as King Peter I. Shortly after his accession, the new king sought out Ines’ killers and enacted his revenge.


As king, Afonso IV of Portugal successfully maintained peace abroad but struggled doing so at home. The Portuguese nobility grew unhappy with the king’s avoidance of war. Similar to his relationship with his father, Afonso also had a strained relationship with his son. After the king’s men assassinated Ines, both Prince Peter and the nobility rebelled against Afonso. By the time he died, the king had left Portugal in a chaotic internal state, but at peace with other countries.


Disney, A. R. (2009). A History of Portugal and the Portuguese Empire: From Beginnings to 1807 (Vol. 1). New York City, NY: Cambridge University Press.

The Editors of Encyclopaedia Britannica. (2020, May 24). Afonso IV. Retrieved July 10, 2020, from


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!

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