Dante & His Fiery Inferno

Although Dante wrote his Divine Comedy in verse, I'd never considered it "epic" before. While reading Canto V, it became apparent that it follows many of the same conventions found throughout the course. Dante's references to characters used in previous works seem especially pertinent. In the second circle of hell are those which are carnal and unable or unwilling to control their physical desires. Dido, Cleopatra, Helen, Achilles, Paris, and Tristan all were doomed to this eternal torment. Dido, Helen, and Paris I can understand the reasoning behind their presence because of the epics which I've studied. (I believe Dido cannot truly be held responsible for her actions because it was the gods that influenced her decision to fall in love. Also Helen and Paris seem to have caused one another enough pain in their mortal existence—it seems cruel to continue their punishment since they were never able to truly enjoy the decision they made.) But I don't quite understand how Achilles ended up there. Achilles did not fight throughout much of Iliad because he was unwilling to humble himself before Agamemnon. Upon hearing Patroclus died, Achilles was filled with a furor that was unmatched. He had a great love and respect for his friend, and fought to honor his friend. I don't see him as one who was unable to control his appetites because in the end, he forfeited every comfort to avenge his friend's death.