The Song of Roland (La Chanson de Roland) is an 11th century Old French epic poem about the battle of Roncevaux (or Roncesvalles) fought by Roland and his fellow paladins. The story details the defense of Charlemagne's army from an attack by Moorish forces.
The account of the song does not match history, but is considered a classic example of the virtues of chivalry.
While returning from the siege of Saragossa to Aix, Emperor Charlemagne's scouts find a large Moorish army approaching from the rear. Roland and the Paladins, along with a division of Charlemagne's army, turn to hold off the Moors while the majority of the army escape.
Roland and his peers put up such a fight that Charlemagne decides to turn around and join the fray. Roland's forces beat back a force a hundred times their own size. All of Roland's men die, but Roland himself in his final act routs the last few Moorish forces.
By the time Charlemagne actually gets to the battle, Roland and the paladins had forced the Moors to flee. Charlemagne ends up defeating the remainder of the Islamic forces before returning to Aix.