Such a perfectly planned ambush in the narrow mountain pass is only possible thanks to Ganelon. He betrays Charlemayn and his stepson, Roland, to join the Saracens. Everything that the emperor planned is now in the hands of his enemies. Such treachery appears to be the result of Ganelon’s grudge against Roland.
In the poem, Ganelon is sent to Saragossa with the envoy, which appears to be his stepson’s idea. He gets so mad that he swears to revenge right that moment. In fact, there might be some other feeling involved, such as jealously. Ganelon wants to take care of that issue so much that he makes a new friend – a Saracen messenger. Together, they plot to kill Roland and try to throw the emperor off the throne. When Ganelon arrives at their kingdom, Saragossa, the king thinks it sounds like a good plan. Besides, they have an advantage. The French traitor tells him everything he knows about Charlemayn and his current location, so the ambush is thought through.
Charlemayn’s army needs to pass the mountain range to get back home to France. However, for their safety, someone needs to stay behind and protect the pass. Roland decides that it is a challenge suitable for his bravery and skills. A part of the soldiers is left with him, and the rest depart with the emperor. Soon enough, the Saracens attack the rear-guard since they knew Roland would be there. And just like that, the Franks lose the battle, being outnumbered and caught by surprise thanks to Ganelon’s betrayal and desire for revenge.