Afonso IV was King of Portugal for more than three decades in the 14th Century. He won a great battle against the Moors but left a kingdom in relative disarray after his own son and heir revolted against him.

Afonso was born on Feb. 8, 1291, in Lisbon. His father was the reigning monarch, King Dinis, and his mother was Isabella of Aragon.

Dinis had two sons named Afonso; the younger had a mother who wasn't Queen Isabella. It was the younger Afonso whom the king favored; by contrast, the queen favored the older, her own son.

Eventually, Afonso tired of his father's favoritism toward his other son and demanded to be named the heir apparent. He ended up going to war with his half-brother, a conflict that lasted two years. According to multiple sources, at one point, Queen Isabella prevented a major confrontation between the two sides by sitting atop a mule in between the two armies, forcing them to negotiate. Afonso the older ultimately prevailed, and it was he who became the new king when Dinis died on Jan. 7, 1325.

Afonso had married Beatrice of Castile in 1309. Their first child, Maria, was born in 1313. They had two other children who lived into adulthood: Peter (1320) and Eleanor (1328).

In an effort to maintain peaceful relations with Castile, Afonso agreed to a marriage between his young daughter and the Castilian monarch, Alfonso XI. Conflict over Alfonso's treatment of his wife led to war between the neighboring kingdoms in 1336. That conflict raged for a few years and then ended in a peace treaty. Soon, the two sides faced a new threat, as Moorish forces from north Africa under the Sultan of Morocco invaded. Afonso IV and Alfonso XI put aside their differences in order to confront a common foe, and the joint army won a great victory at the Battle of Rio Salado, on Oct. 30, 1340. Afonso's acts of daring during the battle earned him the appellation Afonso the Brave.

Afonso could not rest, however, because he had angered both his nobles and his heir, Prince Peter. The heir apparent had gotten married, to Constanza of Castile, in 1340 and they had had two children. When Constanza died, in 1345, Peter declared his intention to pursue a relationship with another woman, named Inês de Castro, who had been Constanza's lady-in-waiting and had a powerful family in Galicia. Peter, defying his father's wishes, went to live with Inês, and they had four children together. Rumors came to King Afonso that his son had fallen under the influence of Inês and her family and was planning to revolt, and the king ordered her imprisoned. Whether at the king's orders or not, a group of men killed Inês. Peter then did revolt against his father.

The rebellion lasted nearly two years before father and son reconciled. Not long afterward, Afonso died, on May 28, 1357. His son became King Pedro I.