Bernardo was said to be the son of Sancho, the Count of Saldana and Dona Jimena (Alfonso II's sister). Alfonso was not happy with the marriage, so he had Sancho blinded and thrown into prison. Alfonso invited Charlemagne into Spain to defeat the Moors, promising to name him as heir. Bernado's victory at Roncesvaux ended that plan. But Bernardo then joined up with the Moors himself, hoping to force Alfonso into action, but Alfonso secretly had Sancho killed while in prison.
In 1624 Bernardo de Balbuena published El Bernardo, an account of Bernardo's exploits. It was once considered one of the masterpieces of Spanish literature.
In the opening of Don Quixote, Cervantes has the Don especially admiring Bernardo because he crushed Roland with his arms alone, although the context is clear that Don Quixote is placing too much credence in the ridiculous stories of romance.
David Burton, The Legend of Bernardo del Carpio: from Chronicle to Drama.References