After Charlemagne’s army invades Umayyad Spain (777), meeting heavy resistance at Zaragoza, Frankish forces suffer a terrible defeat at the hand of the Basques. Among those killed is Roland, Charlemagne’s general. The episode will form the basis of several poetic renderings in which Basques become Moors and Roland’s death is seen as heroic. The most celebrated version of this tale is the 11th century La Chanson de Roland.
Editors. "Battle of Roncevaux". The Literary Encyclopedia. First published 01 May 2009
[http://www.litencyc.com/php/stopics.php?rec=true&UID=6869, accessed 25 September 2016.]