Alfonso VI (1040-1109) became king of León in 1065 and of Castile in 1072. A fighting king of the Spanish Reconquest, he later feuded with the Cid and could not cope with the invading Almoravids.
Alfonso was the second and favorite son of Ferdinand I, Count of Castile and King of León. By the terms of his father's division of the realm, Alfonso became king of León in 1065. (The eldest son, Sancho, became king of Castile, and Galicia was allotted to the youngest son, Garcia.) Relations between Alfonso and Sancho were hostile from the start, and Sancho defeated him at Llantada in 1068. In 1071 the brothers joined temporarily to deprive Garcia of Galicia, but the following year Sancho again worsted Alfonso in battle, taking him prisoner but then allowing him to leave for exile in the Islamic kingdom of Toledo.
Alfonso spent 9 months in Toledo as the guest of the king al-Mamun, departing in October 1072 after his sister Urraca had engineered the assassination of Sancho. Alfonso was now king of Castile, but he was forced by Sancho's chief military aide, Rodrigo Diaz (the Cid), to disavow publicly his complicity in the murder of his brother.
From 1072 to 1086 Alfonso adopted an aggressive policy toward the Moslems. He extorted monetary tributes and in 1085 captured the ancient Visigoth capital of Toledo—his most glorious achievement. During this period he also strove to bring Spain out of isolation and into the orbit of European Christianity; he encouraged foreign pilgrimages to Santiago de Compostela, supported the Pope in supplanting the Spanish Mozarab liturgy with that of the Roman rite, and encouraged the activities of French monks.
The final stage of Alfonso's reign, from 1086 to 1109, was marked by a series of frustrating defeats at the hands of the Almoravid Berbers, who invaded Spain at the behest of Spanish Moslem leaders worried about growing Christian power. On Oct. 23, 1086, Alfonso suffered a humiliating defeat at Sagrajas, after which no Christian troops except those of the Cid were to have any success against the invader. The Cid's success in Valencia served only to deepen the hostility between the King and the former champion of his hated brother. The famous line from Poem of the Cid—"Were his lord but worthy, God how fine a vassal!"— alludes to Alfonso's pettiness and stubborn jealousy in dealing with the Cid, who remained loyal in spite of the King's rebuffs.
After the Cid's death in 1099, Alfonso finally heeded the call of the hero's widow, Jimena, and joined the Cid's troops at Valencia. But that city had to be abandoned to the Almoravids in 1102. The defeats continued unabated until the bitter battle of Uclés in 1108, in which Alfonso suffered the loss of his only son, Sancho. The King died in Toledo on June 30, 1109, leaving his realm in the hands of his daughter, Urraca, and in a state of insecurity and vulnerability from which it was not to recover fully for another century.
A fairly complete narrative of Alfonso's career, particularly episodes involving the Cid, is in Ramón Menéndez Pidal, The Cid and His Spain (trans. 1934). William M. Watt, A History of Islamic Spain (1967), is recommended for general background material.