Charlemagne crossed the Pyrenees at the behest of Muslim opponents of Abd al-Rahman I, but failed to take the city of Zaragoza after its rebellious governor beat Abd al-Rahman's general before Charlemagne even arrived. During his return across the Pyrenees after rampaging through the Basque Country, his rearguard was ambushed and destroyed by the Basques. This battle was later romanticized in the 11th-century chanson de geste, the Song of Roland.