How did Charlemagne help Arab rulers of Barcelone?
In 777, at Paderborn, Charlemagne received envoys from the Arab rulers of Barcelona and Zaragoza. They sought protection from the Umayyad Amir of Cordoba, Abd al-Rahman I, and in 778 Charlemagne led an expedition into the Ebro Valley. The eastern detachment of his forces approached Zaragoza through Barcelona, and the western detachment of his forces crossed the western end of the mountains and descended along the River Ebro. However, one of Charlemagne’s former Arab allies murdered the other, Frankish forces were refused admission to Barcelona, and Zaragoza was held against them. A Umayyad army approached the River Ebro from the south, and Charles was forced to withdraw his army back up the valley and into Francia. In the retreat across the Pyrenees, the rear guard of the Frankish army was slaughtered by Basques forces, and many prominent Frankish officers were killed . Frankish scholar, Einhard, suggests that the military campaigns led by Charlemagne were skilfully conducted and well-planned . However, by contrast, Collins believes that the campaigns in Italy and Spain enabled the Saxons to rebel against Frankish rule. In particular, he describes the Spanish expedition as ill-conceived and the closest Charlemagne came to disaster. This suggests that Charlemagne may have been excessively ambitious because the Spanish campaign left the Franks vulnerable to Saxon rebellion. In summary, the Spanish campaign led by Charlemagne was a complete failure which allowed the Saxons to rise up against the Franks, and this has been omitted by Frankish sources to portray the Frankish King as unrelentingly triumphant.
To conclude, Frankish sources have idealized the life and achievements of Charlemagne to portray the Frankish King as a flawless military leader. He suffered a small number of defeats at the hands of Saxon and Spanish forces which have been omitted by Frankish sources. However, overall, he nevertheless deserves to be called Charles the Great because he was an exceptionally skillful and charismatic leader, and held many titles simultaneously in a way which was unforeseen.