Which epic poem tells of Aeneas fleeing Troy?

The Aeneid, written by Virgil over the last eleven years of his life and left unfinished - he asked on his deathbed for it to be burned, and Augustus overruled him, which is why it exists.

It was a commission in all but name. Rome had won a civil war and needed a founding myth connecting it to the prestige of Greek epic, and Virgil supplied one: a Trojan prince escapes the sack of Troy carrying his father on his back, wanders, and founds the line that leads to Rome - and, by explicit prophecy, to Augustus. It is propaganda of an unusually high order.

It also keeps undercutting itself, which is why it survived being useful. Aeneas is defined by duty and is not much liked by readers; he abandons Dido, who kills herself and curses his descendants, supplying a mythic origin for the wars with Carthage. And the poem ends abruptly with Aeneas killing a defeated, begging enemy in a rage - the founder of Rome, in his last appearance, doing exactly what the poem's stated values forbid. Scholars have argued for two thousand years about whether that is unfinished or the point.