Dom Afonso I (born Afonso Henriques; 1106/1109/1111 – 6 December 1185) nicknamed "the Conqueror" (Portuguese: O Conquistador), "the Founder" (O Fundador) and "the Great" (O Magno) by the Portuguese, was the first king of Portugal, from 26 July 1139 until his death on 6 December 1185. He achieved the independence of the County of Portugal, establishing a new kingdom and doubling its area with the Reconquista, an objective that he pursued until his death.
Afonso was the son of Theresa of León and Henry of Burgundy, rulers of the County of Portugal. Henry died in 1112, leaving Theresa to rule alone. 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, Afonso renounced the suzerainty of the Kingdom of León and established the independent Kingdom of Portugal.
Afonso actively campaigned against the Moors in the south. 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. He secured the independence of Portugal following a victory over León at Valdevez and received papal approval through Manifestis Probatum. Afonso died in 1185 and was succeeded by his son, Sancho I.
Afonso was the son of Theresa, the illegitimate daughter of King Alfonso VI of León, and her husband, Henry of Burgundy. He was the youngest of 3 children, with the oldest being Urraca Henriques and Sancha Henriques being the middle child. Historians have also come to a consesus that a fourth illegitimate child was born from Henry of Burgundy, namely Pedro Afonso, who followed on his half-brother's conquests and later settled as a monk in Alcobaça Monastery.
His place of birth has been highly disputed between scholars and historians, with four distinct possibilities: 1) he was born in Guimarães, which was an important fortified position in the County of Portugal; 2) he was born in Viseu, which was an important economic hub for the County; 3) he was born in Coimbra, an immensely important city where he would later spent the most time in and be buried in; or 4) he was born elsewhere, either Tierra de Campos, Sahagún or Braga.
According to the Crónica de Portugal de 1419 the future Portuguese king was born in Viseu, which was at the time the most important political centre of his parents. This was accepted by most Portuguese scholars until 1990, when Torquato de Sousa Soares proposed Coimbra, the centre of the county of Coimbra and another political centre of Afonso's progenitors, as his birthplace, which caused outrage in Guimarães and a polemic between this historian and José Hermano Saraiva. Almeida Fernandes later proposed Viseu as the birthplace of Afonso based on the Chronica Gothorum, which states Afonso was born in 1109, a position followed by historian José Mattoso in his biography of the king, regardless of this, it is still widely accepted in popular conscience that Afonso was born in Guimarães. Abel Estefânio has suggested a different date and thesis, proposing 1106 as the birth date and the region of Tierra de Campos or even Sahagún as likely birthplaces based on the known itineraries of Henry and Theresa.
His place of baptism is also under suspicion: according to tradition the place is indicated as being in the Church of São Miguel do Castelo, in Guimarães, however, recent scholarship, backed by architectural and archeological evidence, have cast doubts on this claim. It has been calculated that the date of the consecration of the Church took place in 1239, therefore putting the construction of the church an entire century after his birth. There are those who argue that the baptism actually took place in the Cathedral of Braga where he was baptised by the Primate Archbishop Saint Gerald of Braga, which was a politically sound move for Count Henry to have the highest-ranking clergy in his fiefdom baptise his heir.
Henry and Theresa reigned jointly as count and countess of Portugal until his death on 22 May 1112 during the siege of Astorga, after which Theresa ruled Portugal as a widow. Both women, Countess Theresa and Queen Urraca, ruled alone after the deaths of their immigrant husbands, ostensibly in defence of their young children, but also in their own right. Theresa 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.
It is not known who was the tutor of Afonso. Later traditions, probably started with João Soares Coelho (a bastard descendant of Egas Moniz through a female line) in the mid-13th century and ampliated by later chronicles such as the Crónica de Portugal de 1419, asserted he had been Egas Moniz de Ribadouro, possibly with the help of oral memories that associated the tutor to the house of Ribadouro. Yet, contemporary documents, namely from the chancery of Afonso in his early years as count of Portucale, indicate according to Mattoso that the most likely tutor of Afonso Henriques was Egas Moniz's oldest brother, Ermígio Moniz, who, besides being the senior brother within the family of Ribadouro, became the "dapifer" and "majordomus" of Afonso I from 1128 until his death in 1135, which indicates his closer proximity to the prince.
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. The Portuguese nobility disliked the alliance between Galicia and Portugal and rallied around Afonso. The Archbishop of Braga, Maurice Bourdin, was also concerned with the dominance of Galicia, apprehensive of the ecclesiastical pretensions of his new rival the Galician Archbishop of Santiago de Compostela, Diego Gelmírez, who had claimed an alleged discovery of relics of Saint James in his town, as a way to gain power and riches over the other cathedrals in the Iberian Peninsula. In order to stop her son Afonso from overthrowing her, Theresa exiled him when he was twelve in the year 1120. In 1122, Afonso turned fourteen, the adult age in the 12th century. In symmetry with his cousin Afonso VII, Afonso Henriques made himself a knight on his own account in the Cathedral of Zamora in 1125. After the military campaign of Alfonso VII against his mother in 1127, Afonso revolted against his own and proceeded to take control of the county from its ruler.
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. Afonso exiled his mother to Galicia, and took over rule of the County of Portucale. 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. The battle was mostly ignored by the Leonese suzerain, who was occupied at the time with a revolt in Castile. He was also, most likely, waiting for the reaction of the Galician families. After Theresa's death in 1131, Alfonso VII of León proceeded to demand vassalage from his cousin. On 6 April 1129, Afonso Henriques dictated the writ in which he proclaimed himself Prince of Portugal or Prince of the Portuguese, an act informally allowed by Alfonso VII, as it was thought to be Afonso Henriques's right by blood, as one of two grandsons of the Emperor of Hispania.
Afonso then turned his arms against the persistent problem of the Moors in the south. 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.