The supposed icon of the “Spanish reconquest” actually spent much of his career defending Muslim kingdoms against their Muslim and Christian enemies

And so it was that when the armies of the two taifa kingdoms clashed at the Battle of Cabra in 1079, each was led by a detachment of Castilian knights. The commander of those supporting al-Mu’tamid was a seasoned warrior named Rodrigo de Vivar. When he routed ‘Abd Allah’s forces and their leader, his bitter enemy Garcia Ordoñez, the Muslim troops of the Sevelle acclaimed Rodrigo as al-sayyid (“lord,” in Arabic), which his Castilian countrymen imitated, calling him El Cid. The supposed icon of the “Spanish reconquest” actually spent much of his career defending Muslim kingdoms against their Muslim and Christian enemies.

B. Catlos, Kingdoms of faith (2018) 220