Ramiro I
As a young man in 1057, Rodrigo fought against the Moorish stronghold of Zaragoza, making its emir al-Muqtadir a vassal of Sancho. In the spring of 1063, Rodrigo fought in the Battle of Graus, where Ferdinand's half-brother, Ramiro I of Aragon, was laying siege to the Moorish town of Graus, which was fought on Zaragozan lands in the valley of the river Cinca. Al-Muqtadir, accompanied by Castilian troops including El Cid, fought against the Aragonese. The party slew Ramiro I, setting the Aragonese army on the run, and emerged victorious. One legend has said that during the conflict, El Cid killed an Aragonese knight in single combat, thereby receiving the honorific title "Campeador".