He became renowned for his military prowess in these campaigns, which helped expand the territory of the Crown of Castile at the expense of the Muslims and Sancho's brothers' kingdoms.

When conspirators murdered Sancho in 1072, El Cid found himself in a difficult situation. Since Sancho was childless, the throne passed to his brother Alfonso, whom El Cid had helped remove from power. Although El Cid continued to serve the sovereign, he lost his ranking in the new court, which treated him suspiciously and kept him at arm's length. Finally,