That battle is arranged through the treachery of Ganelon, and sees the death of Olivier and Turpin after the title character sounds the oliphant of Charles Martel.
In it, the story of Basan and Basil is told as a warning, but that warning is not heeded. A similar warning in this story comes in two dreams, one concerning a hound defending the dreamer from a bear and leopard, the other about a traitor shaking the dreamer's lance until the lance shatters. In this story, the arrival of a fleet from Babylon fails to change the outcome when Baligant is defeated, and the earlier conniving of Blancandrin leads to Aelroth gathering Falsaron, Corsablis, and Margariz for battle. That battle is arranged through the treachery of Ganelon, and sees the death of Olivier and Turpin after the title character sounds the oliphant of Charles Martel. For 10 points, name this work in which Charlemagne's army twice avenges the death of the title hero, an anonymous work from 12th century France.
In it, the story of Basan and Basil is told as a warning, but that warning is not heeded.
Song of {Roland} or {Chanson} de {Roland}