Roland blows his oliphant so hard that his temple bursts, badly wounding him. Charlemagne and his men hear him, far in the distance. Charles understands the signal, knows that the rear guard is embattled. But Ganelon tries to stall the emperor's troops, tries to convince Charlemagne that he's senile and hearing things, then that Roland is just blowing the oliphant to show off, that, in any case, the rear guard is in no danger and that they should ride on into France. The barons realize that Ganelon is a false traitor trying to deceive them to stop them from helping Roland, and they arrest Ganelon, telling the camp cooks to stay there and guard him "like any common thug" (137.1819). The Frankish army ride off in the direction of the sound of the horn blasts.
Back on the battlefield, meanwhile, Roland surveys the heaps of dead and dying Christian soldiers around him, weeps, laments, and prays to God to deliver their souls to heaven. But he continues to fight gallantly despite his great grief and his injury, cutting off Marsilla's right hand. Olivier is mortally wounded, but likewise continues to fight as his life slips away. Seeing Olivier hurt so, Roland faints, still on his horse. As death nears, Olivier's vision is confused because he has lost so much blood, and, in the blur of it, he does not recognize Roland and gives him a blow to the head, splitting his comrade's helmet but not cutting into his skull. Roland softly asks Olivier if he meant that blow; Olivier recognizes his voice and apologizes and Roland forgives him. Knowing that death is upon him, Olivier gets off his horse and prays before dying, and Roland weeps for the death of his companion, fainting away from the grief of it.
When Roland recovers, he looks around and sees that, of all the rear guard, only Turpin and Gautier, who just came down from the mountains, are still alive. The three Franks remaining are stalwart warriors, but they are mightily outnumbered. Gautier is soon killed and Turpin is soon injured and unhorsed. Roland again sounds his oliphant; hearing the feebleness of the blast, Charlemagne can tell that his nephew has not long to live. Riding fast toward the battlefield, Charlemagne's men blow their trumpets.
Hearing the trumpets, the pagans start with terror, knowing that the emperor is on his way. They make one last attack on Roland and flee; when the Saracens have left, Roland and Turpin are still standing, though mortally wounded.
While Roland blows his oliphant in laisses 133 through 135, a sense of urgency is built up by the narration's alternation between him and Charlemagne's army. Within each of these laisses we see both the mortal injury Roland receives by blowing so mightily on his horn and the stalling technique of the traitor Ganelon, both of which contribute to our fear that Charlemagne and his men may come too late.
When the main Frankish army rides back to Roncesvals, we are given once again a variation on the ominous description of the landscape around this massacre ground, which we've heard before; here is another of the repetitions that holds the poem together. In laisse 66 we are given the picture that follows: "The hills are high, the valleys deep in shade, / with dull brown cliffs and awe-inspiring gorges." Here we get a slight variation: "The hills are high and shadowy and large, / the valleys deep, with swiftly running streams" (138.1830- 1831).