Charlemagne's wars were chiefly against the pagan and barbarous people, who, under the name of Saxons, inhabited the countries now called Hanover and Holland. He also led expeditions against the Saracens of Spain; but his wars with the Saracens were not carried on, as the romances assert, in France, but on the soil of Spain. He entered Spain by the Eastern Pyrenees, and made an easy conquest of Barcelona and Pampeluna. But Saragossa refused to open her gates to him, and Charles ended by negotiating, and accepting a vast sum of gold as the price of his return over the Pyrenees.The Song of Roland is generally dated to the late eleventh century, and tells the story of the betrayal and death of Roland (in Frankish, Hruodlandus), nephew of Charlemagne, in the Basque country of Roncesvalles.
On his way back, he marched with his whole army through the gorges of the mountains by way of the valleys of Engui, Eno, and Roncesvalles. The chief of this region had waited upon Charlemagne, on his advance, as a faithful vassal of the monarchy; but now, on the return of the Franks, he had called together all the wild mountaineers who acknowledged him as their chief, and they occupied the heights of the mountains under which the army had to pass. The main body of the troops met with no obstruction, and received no intimation of danger; but the rear-guard, which was considerably behind, and encumbered with its plunder, was overwhelmed by the mountaineers in the pass of Roncesvalles, and slain to a man. Some of the bravest of the Frankish chiefs perished on this occasion, among whom is mentioned Roland or Orlando, governor of the marches or frontier of Brittany. His name became famous in after times, and the disaster of Roncesvalles and death of Roland became eventually the most celebrated episode in the vast cycle of romance. [Thomas Bulfinch, Legends of Charlemagne, or Romance of the Middle Ages, 1863]
In the Renaissaance, the story of Roland formed the seed for two fantastical romances Orlando Innamorato (Roland in Love) (1495) by Matteo Maria Boiardo (left unfinished at the author's death) and a continuance, Orlando Furioso (Roland Enraged) (1516) by Ludovico Ariosto.