Unhappy with Theresa's romantic relationship with Galician Fernando Pérez de Traba and his political influence, the Portuguese nobility rallied around Afonso, who revolted and defeated his mother at the Battle of São Mamede in 1128 and became sole Count of Portugal soon afterwards.

In 1139 he won a decisive victory at the Battle of Ourique, and in 1147 he seized Santarém and Lisbon from the Moors, with help from men on their way to the Holy Land for the Second Crusade.

[10] She would proclaim herself queen (a claim recognised by Pope Paschal II in 1116) but was captured and forced to reaffirm her vassalage to her half-sister, Urraca of León.

[11][12] In an effort to pursue a larger share in the Leonese inheritance, his mother Theresa joined forces with Fernando Pérez de Trava, the most powerful count in Galicia.

In 1128, near Guimarães at the Battle of São Mamede, Afonso and his supporters overcame troops under both his mother and her lover, Count Fernando Pérez de Traba of Galicia.

[10] Thus the possibility of re-incorporating Portucale into a Kingdom of Portugal and Galicia as before was eliminated and Afonso became sole ruler following demands for greater independence from the county's church and nobles.

His campaigns were successful and, on 25 July 1139, he obtained an overwhelming victory in the Battle of Ourique, and straight after was (possibly unanimously) proclaimed King of the Portuguese by his soldiers, establishing his equality in rank to the other realms of the Peninsula, although the first reference to his royal title dates from 1140.

In 1143, he wrote to Pope Innocent II to declare himself and the kingdom servants of the church, swearing to pursue driving the Moors out of the Iberian Peninsula.

He spent months at the hot springs of São Pedro do Sul, but never recovered and from this time onward the Portuguese king never rode a horse again.

However, it is not certain if this was because of the disability: according to the later Portuguese chronistic tradition, this happened because Afonso would have to surrender himself again to Ferdinand or risk war between the two kingdoms if he ever rode a horse again.

Portugal was obliged to surrender as his ransom almost all the conquests Afonso had made in Galicia (north of the Minho River) in the previous years.

[13] There are mythical stories that it took ten men to carry his sword, and that Afonso wanted to engage other monarchs in personal combat, but no one would dare accept his challenge.

Several chronicles give the example of a papal legate that brought a message from Pope Paschal II refusing to acknowledge Afonso's claim as king: either after committing or saying a small offense against him or after being simply read the letter, Afonso almost killed, in his rage, the papal representative, and it took several Portuguese nobles and soldiers to physically restrain the young would-be king.

[14][15] In 1146,[b] Afonso married Mafalda, daughter of Amadeus III, Count of Savoy and Mahaut of Albon, both appearing together for the first time in May of that year confirming royal charters.