The poem is about an actual historical event that happened centuries earlier. In 778 Charlemagne invaded Spain. On his way through the Pyrenees he looted and plundered Basque lands. He found little resistance in Spain until he reached the city of Zaragoza. Charlemagne demanded they surrender. The city governor, Hussain Ibn al-Ansari, refused. Charlemagne then laid siege to the city but with little success. Finally the governor paid Charlemagne a large amount of gold in return for Charlemagne's army leaving the area. Charlemagne had a pending Saxon revolt at home so he needed little persuasion to leave.