Alfonso VI reunited León, Castile and Galicia, captured Toledo in 1085, and styled himself emperor of Spain — but his triumph brought the Almoravids into Iberia and the great defeat of Sagrajas.
Alfonso VI of León and Castile ruled from 1065 to 1109 and was the dominant Christian king of his age. He reunited the realms his father Ferdinand I had divided, imposed tribute on the Muslim taifa kingdoms, and in 1085 captured Toledo, the old Visigothic capital.
His success was checked the next year at Sagrajas, where the newly arrived Almoravids destroyed his army. His reign thus spans both the high tide of eleventh-century Christian expansion and the reaction that halted it.
Alfonso inherited León in 1065 and, after the deaths of his brothers Sancho II and García in the wars over their father's partitioned inheritance, reunited León, Castile and Galicia by 1072. He turned the taifa kings into tributaries, drawing vast wealth in parias, and in 1085 crowned this dominance with the conquest of Toledo.
The taifa appeal to the Almoravids brought disaster at Sagrajas in 1086, and later defeats — including Uclés in 1108, where his only son Sancho was killed — clouded his last years. His relationship with the great Castilian warlord El Cid was famously stormy, marked by exile and reconciliation. He died in 1109, leaving his daughter Urraca to succeed.
Alfonso VI comes across as an ambitious, calculating ruler, as ready to use and depose the taifa kings as to fight them, and grand enough to claim the title of "emperor of all Spain". His long manipulation of Toledo before taking it shows a patient, political style of conquest.
He could also be harsh and proud — his quarrels with El Cid, whom he exiled, reveal a suspicious streak — yet he was pragmatic in ruling a mixed society, confirming protections for Muslims and Jews at Toledo. Contemporaries saw him as formidable, and his defeats wounded a reputation built on real achievement.