Ferdinand I of Castile, El Magno or "the Great," (d. 1065), son of Sancho III of Navarre, was put in possession of Castile in 1028 with his father's backing, on the murder of the last Count, as the heir of his mother Elvira, daughter of a previous count of Castile. The count, Don García, was about to be married to Doña Sancha, sister and presumed heiress of Bermudo, king of León, but was assassinated as he was entering the church of San Juan Bautista in León by a party of Castilian nobles, exiles from their own country, who had taken refuge in Leon.
Ferdinand now married Sancha instead. He reigned in Castile with the title of king from 1033. In 1038, when his father-in-law Bermudo was killed in battle with Ferdinand at Tamaron, Ferdinand took possession of León as well, by right of his wife. He overran the Moorish section of Galicia, and set up his vassal as count in what is now northern Portugal. With northern Spain consolidated, Ferdinand, in 1056, proclaimed himself emperor of Hispania. The use of the title was resented by the emperor Henry II, Holy Roman Emperor supported by Pope Victor II in 1055, as implying a claim to the headship of Christendom, and as a usurpation on the Holy Roman Empire. It did not, however, mean more than that the sovereign of León was the chief of the princes of the peninsula, and that Spain was independent of the Empire.
Although Ferdinand had grown in power by this strife with Bermudo of León, and though at a later date he defeated and killed his brother García of Navarre, he ranks high among the kings of Spain who have been counted religious. To a large extent he may have owed this reputation to the military victories over the Moors, in which he initiated the period of the Christian reconquest of the peninsula.
But there can be no doubt that Ferdinand was profoundly pious. Towards the close of his reign he sent a special embassy to Seville to bring back the body of Santa Justa. The then king of Seville, Motadhid, one of the local princes who had divided the caliphate of Cordova, was himself a sceptic and poisoner, but he stood in wholesome awe of the power of the Christian king. He favoured the embassy in every way, and when the body of Santa Justa could not be found, helped the envoys, who were also aided by a vision seen by one of them in a dream, to discover the body of Isidore of Seville instead. The Doctor's body was reverently carried away to León, where the church of San Juan Bautista was reconsecrated to receive the relics.
Ferdinand died on the feast of Saint John the Evangelist, June 24, 1065, in León, with many manifestations of ardent piety, having laid aside his crown and royal mantle, dressed in the robe of a monk and lying on a bier covered with ashes, which was placed before the altar of the church of Saint Isidore.