Afonso I of Portugal

Afonso I of Portugal
c. 1109/1111 – December 6, 1185

Afonso I of Portugal was born between 1109/1111 in Guimaraes, Portucale (Portugal). Through his parents, the young nobleman had a prestigious pedigree. Afonso’s father, Henry of Burgundy, descended from the French Capetian dynasty. Afonso’s mother, Teresa, was Emperor Alfonso VI of Leon’s illegitimate daughter.

Henry of Burgundy had initially come to Portucale through a family connection. Alfonso’s wife, Queen Constance, was Henry’s aunt. In 1095, the emperor split the territory of Gallaecia between Henry and his distant relative, Raymond of Burgundy. In turn, Henry received Portucale while Raymond obtained Galicia. As the count of Portucale, Henry secured his position by marrying Alfonso’s daughter, Teresa.

Over the years, Henry successfully defended his county from Muslim attacks. Although Alfonso VI’s vassal, Henry took steps to become more independent after the emperor’s death in 1109. Upon his death in 1112, Teresa ruled Portucale on behalf of their infant son, Afonso. As a widow, Teresa faced pressure to re-marry. Instead of marrying someone from Portucale, Teresa came under the influence of a Galician family: the Tavas.

 Fight for Control

The Tavas had connections to Raymond of Burgundy’s court and had gained influence over his heir. They sought to re-unite Galia with Portucale. To accomplish this, Fernando Peres de Trava seduced Teresa and convinced her to marry her daughter to a Trava. In turn, Portucale’s nobility opposed the Trava’s growing power. The last straw occurred in 1121 after Teresa appointed Fernando as governor. By 1127, Teresa and the Travas faced a revolt by the nobility.

Leading the nobility was Afonso. The young nobleman had been raised amongst the nobility and shared many of their values. He had also gained military experience after defending Guimaraes from his cousin, Emperor Alfonso VII. After his mother refused to hand over his birthright, Afonso joined the revolt. On June 24, 1128, Afonso’s forces fought his mother’s at the Battle of Sao Mamede. After suffering defeat, Teresa and the Travas fled to Galicia.

Founding a Kingdom

12th Century Iberian Peninsula
12th Century Iberian Peninsula

Upon securing his hold of Portucale, Afonso controlled a sizeable portion of the western Iberian Peninsula. In 1131, the nobleman moved his capital south from Guimaraes to Coimbra. Afonso did so to secure his southern border and to engage in the Reconquest. The Reconquest was a Christian military campaign to expel Iberian Muslims from the peninsula. After engaging Muslim forces at the Battle of Ourique in 1139, Afonso’s victory convinced him to declare himself king of Portugal.

Despite having the support of his subjects, Afonso I still had to gain recognition from other rulers. The most important was the approval of Emperor Alfonso VII. Although neighboring Castile and Aragon also had kings, they still had to answer to the emperor. In 1143, both men met to reach an agreement. After mediation, Alfonso acknowledged Afonso as king, while the latter promised to respect the emperor’s borders.

To increase his prestige, Afonso I focused on expanding Portugal’s southern border. Over the following decades, Afonso pushed his kingdom’s borders beyond the Tagus River. By the 1160s, the king controlled many vital towns such as Santarem, Beja, and Evora. Through his conquests, Afonso demanded tribute payments from his new Muslim subjects.


Despite Afonso I’s success, he would be captured during the siege of Badajoz in 1169. King Ferdinand II of Leon didn’t want Afonso to capture Badajoz and offered aid to the town’s defenders. After suffering a leg wound while fighting, Afonso would be captured. In turn, the Portuguese king would be Ferdinand’s prisoner for an unknown period of time. Eventually, Afonso regained his freedom and returned to Portugal.

Final Years

Upon his return, the aging Afonso I began delegating his responsibilities to his heir, Sancho. In turn, the prince inherited many problems, including the growing power of a Muslim group called the Almohads. Originating in the Atlas Mountains, the Almohad army crossed into the peninsula in 1171. During the 1170s to early 1180s, the Almohads pushed back Portugal’s border to the Tagus River. As Sancho fought against the Muslims, Afonso died on December 6, 1185.


Afonso I of Portugal rose from a count to a king. Through his leadership, Afonso created an independent kingdom in the Iberian peninsula. He established Portugal’s prestige by expanding its borders and overcoming his enemies. Although the Almohads had retaken some of his territory, the king left behind a stable and prosperous monarchy to his son.


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.

Afonso I. (n.d.). Retrieved February 16, 2021, 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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