The encounter between Leo the Great and Attila is the last fresco painted in this room. It was commissioned by Pope Julius II to commemorate the Battle of Ravenna (1512), which forced the French to retreat from Italy. Raphael depicted Cardinal Giovanni de'Medici, present at the Battle of Ravenna, on a gray mule at the left, and intended to portray Leo the Great with the features of Pope Julius II.

Julius II died in 1513, and Cardinal Giovanni de'Medici succeeded him to the papal throne as Leo X (pontiff from 1513 to 1521). Raphael then depicted Leo the Great with the features of the new pope, who therefore appears twice in this scene.

According to legend, the miraculous apparition of Saints Peter and Paul armed with swords during the meeting between Pope Leo the Great and Attila (452 A.D.) caused the king of the Huns to desist from invading Italy and marching on Rome. Raphael situates the scene at the gates of Rome, identified by the Colosseum, by an aqueduct, an obelisk and other buildings, even if in fact the historical event took place in the north of Italy, near Mantua.