To meet this revival of Mohammedan power, Alfonso VI. Of Castile summoned the chivalry of Christendom to his aid. Among the knights who answered the call was Count Henry of Burgundy (grandson of Robert, first Duke of Burgundy) to whom Alfonso gave his natural daughter Theresa in marriage, together with the Counties of Oporto and Coimbra, with the title of Count of Portugal. That is the first chapter of the history of Portugal. Count Henry fought hard to defend his southern frontiers from the incursion of the Moors until his death in 1114. Thereafter his widow Theresa became Regent of Portugal during the minority of their son, Affonso Henriques. A woman of great energy, resource and ambition, she successfully waged war against the Moors, and in other ways laid the foundations upon which her son was to build the Kingdom of Portugal. But her passionate infatuation for one of her knights—Don Fernando Peres de Trava—and the excessive honours she bestowed upon him, made enemies for her in the new state, and estranged her from her son. In 1127 Alfonso VII. of Castile invaded Portugal, compelling Theresa to recognize him as her suzerain. But Affonso Henriques, now aged seventeen—and declared by the citizens of the capital to be of age and competent to reign—incontinently refused to recognize the submission made by his mother, and in the following year assembled an army for the purpose of expelling her and her lover from the country. The warlike Theresa resisted until defeated in the battle of San Mamede and taken prisoner. He was little more than a boy, although four years were sped already since, as a mere lad of fourteen, he had kept vigil throughout the night over his arms in the Cathedral of Zamora, preparatory to receiving the honour of knighthood at the hands of his cousin, Alfonso VII. of Castile. Yet already he was looked upon as the very pattern of what a Christian knight should be, worthy son of the father who had devoted his life to doing battle against the Infidel, wheresoever he might be found. He was well-grown and tall, and of a bodily strength that is almost a byword to this day in that Portugal of which he was the real founder and first king. He was skilled beyond the common wont in all knightly exercises of arms and horsemanship, and equipped with far more learning—though much of it was ill-digested, as this story will serve to show—than the twelfth century considered useful or even proper in a knight. And he was at least true to his time in that he combined a fervid piety with a weakness of the flesh and an impetuous arrogance that was to bring him under the ban of greater excommunication at the very outset of his reign.