Treason, in whatever age and under whatever conditions, cuts to the heart of the human condition, since it ruptures those bonds of trust on which we base our lives. The gravity of the deed explains its perennial appeal, particularly when it destroys not only trust but also lives, as is the case with those epics dealing with the betrayal of Roland, the nephew of the great Frankish emperor, Charlemagne. Turoldus's Old French Chanson de Roland, written around 1100, describes the ambush of Charlemagne's rear guard by Muslims in Spain — an ambush arranged in this work by none other than Roland's stepfather Ganelon, in collusion with Islamic rulers supposedly under Charlemagne's control. Forbidden by Charlemagne to head the delegation to the Muslims, Roland nominates Ganelon, known for his wisdom and valor. Ganelon, using the prerogative of the feud, determines to seek revenge and betrays Roland and the Frankish rear guard to the Muslims for a considerable sum of money. After Roland's death, he is brought to trial, complete with a judicial duel to decide his fate, and is executed.

The power struggles in this work — between Charlemagne and Ganelon, Charlemagne and his peers, the Carolingians and the Muslims, and Roland and Ganelon — plus the high drama of a trial for treason ensured its popularity as a narrative, as the late medieval German versions of this story attest. The Chanson de Roland is the most famous of the chansons de geste, which have as their subject matter the legendary history of the Carolingian world.