The source of the story in the tapestries is pseudo-Turpin's version of the <i>Chanson de Roland</i> and especially <i>La Bataille de Rainchevaux</i>, a 13th century account deriving from pseudo-Turpin. The real battle was the last of Charlemagne's first campaign to capture Spain, an attempt that ended in failure. Roland and the rear guard were left behind the main army, and were attacked at the Roncevaux pass in the Pyrenees by the Basques on August 15, 778, when the Franks were completely annihilated. This minor battle was romanticized by oral tradition into a major conflict between Christians and Saracens (both sides were Christians), where Charlemagne comes to the resue of Roland and destroys the Saracens. When <i>The Song of Roland</i> was written down, by an unknown troubadour of the 11th century, it became the first chanson de gest or epic poem of medieval France.