In a rage at the turn of events against the Latins, Turnus announces to Latinus his intention to fight Aeneas and win Lavinia's hand. Latinus begs Turnus to reconsider, but Turnus is resolute. He says he's strong enough, and Venus won't be able to protect Aeneas when they fight man-to-man. Amata cries that if Turnus dies, she'll die too, rather than see her daughter with Aeneas. Turnus tells Amata, whom he calls "mother," not to bother him further with her fears. Tomorrow he'll fight Aeneas. He puts on his armor, including his special sword, inherited from his father, which was made by Vulcan and dipped in the river Styx.
It seems that Turnus's sword may be able to get past Aeneas's shield, since both were made by Vulcan, but given the attitude of Latinus's family no one believes that Turnus can actually win. Nonetheless, he bravely plans to fight Aeneas (and fate). The love that the Latin royal family feels for Turnus, and the way they already treat him as a son, ensures that no matter who wins this battle, it will be a tragedy.
On the Trojan side, Aeneas accepts Turnus's challenge, and comforts his friends and Ascanius by talking about fate. Morning comes and both armies march to the battlefield, not to fight but to accompany their leaders for the duel. Juno, watching from a nearby mountain, speaks to Turnus's sister Juturna, a nymph of lakes. Juno explains that she's been helping Turnus, and tells Juturna to go try to stop Turnus's fate, because Juno can't bear to watch the fight. Or, Juno says, Juturna could stir up the war again.
Aeneas's friends are much less concerned about him battling Turnus, since fate is on his side. Juno reaches a turning point in her harassment—knowing she's on the losing side, she can't bear to be directly involved. This demonstrates both her pride and her love for Turnus.
Latinus, Turnus, and Aeneas enter in separate chariots. Aeneas prays and asks Juno to be more kind. He says the Trojans will leave peacefully if he falls, but he hopes that instead of enslavement or humiliation of one side, the Trojans and Latins will "undefeated, under equal laws, march together towards an eternal pact of peace." Latinus agrees and they sacrifice animals.
The Rutulians are nervous to see how uneven the duel will be, with Turnus looking scared and weak compared to Aeneas. Juturna sees her chance, and, disguising herself as the soldier Camers, she tells the Rutulians they should fight or they'll be enslaved. The other allies on Turnus's side also get riled up, and then Juturna makes a sign—an eagle, the bird of Jove, snatches a swan from the stream, but has to drop the swan when other birds attack it. The Latins, encouraged by the seer Tolumnius, think this means that they, like the smaller birds, can win.
Juturna tries both to cheat fate (and save Turnus) and fake fate (with a sign). The scene again shows that humans interpret signs in the way that fits with their worldview. Virgil here shows us Turnus from the Latin point of view, making it impossible for us to fully cheer for Aeneas without feeling a pang for poor Turnus.
A Latin named Tolumnius throws a spear which kills A Trojan, restarting the war. With his peace efforts destroyed, Latinus runs back to his city. Aeneas attempts to regain control of the situation, but an arrow hits him. The name of the shooter is unknown, since no one ever wanted to boast of having hit Aeneas. Seeing this, Turnus regains hope and kills many men. Achates and Ascanius, along with Mnestheus, another Trojan, bring Aeneas back to the camp. Aeneas wants them to cut him open to take out the arrowhead so he can go fight again.
Virgil, as the creator of the Aeneid, of course could have made it that the name of the person who shot the arrow that killed Aeneas was known. But he makes Aeneas seem even greater by imagining how even his enemies would have respected him and wouldn't have found any glory in gloating about causing him injury.
Iapyx, a healer and favorite of Apollo, tries to pull out the arrowhead, without success, since Apollo refuses to intervene. Venus flies to Crete to pick some dittany, a healing herb, and then invisibly mixes it into Iapyx's treatment. The arrow now comes out easily, and Aeneas feels well enough to fight. Iapyx realizes that his human skills couldn't have cured Aeneas—it's a god's work.
Apollo doesn't help to cure Aeneas, but Venus does. This highlights the way that the gods play favorites. Surprisingly, despite Aeneas's status as a great hero and forefather of Augustus, not all the gods rally behind him.
Aeneas's return to the battle demoralizes the Latins and the Trojans kill many enemies. Juturna sees Aeneas stalking Turnus. She pushes Metiscus, Turnus's chariot-driver, out of his seat, taking the reigns and using her nymph-powers to disguise herself as him. She steers the chariot far from Aeneas.
Juturna's dedication to her brother makes him a more sympathetic character. Despite Turnus's anger (which might be more Juno's fault than his), he's brave and important to his people. Like when Juno tricked him into getting on a boat, here his sister, attempting to protect him, makes him seem more cowardly.
Messapus, Turnus's ally and a son of Neptune, knocks off Aeneas's helmet with a spear. Aeneas, frustrated by this and by Turnus's flight, gives up just trying to find Turnus for the duel, and throws himself fully into the battle. He kills so many people so ferociously that Virgil wonders what god can even help him sing about all the slaughter. Virgil wonders if Jove liked seeing all this: "Did it please you so, great Jove, to see the world at war, the peoples clash that would later live in everlasting peace?"
The battle is so horrible it defies not only Virgil's powers to describe it, but also the powers of the muses. His ironic question to Jove dramatically details the ruinous pointlessness of this war, and makes a larger point too. How can we continue to believe in gods in the face of such a disaster? Even piety is thrown into doubt. At the same time, it also highlights the Roman's great ability to create peace, as opposed to war.
Venus suggests to Aeneas that he attack Lavinium. Aeneas agrees. As the Trojans rush into Lavinium, Aeneas yells to the gods that the Latins have broken two pacts and so he's been forced back into war.
Though Aeneas is responsible for much of the carnage, he also hates the war. He defends his actions by blaming the Latins, and he's right—to achieve his fate, he doesn't have another option.
Amata, the queen, sees the attacking Trojans and thinks that this means that Turnus has died. Believing this terrible outcome is all her fault, she makes a noose from her dress and hangs herself. Lavinia and the other women mourn, and Latinus puts dirt on his head in sorrow.
Amata commits suicide because she believes her stance against Aeneas started the war that is now going so badly. But she only took that stands after Juno sent Allecto to enchant her. Amata's death ensures that even a Trojan victory will not restore total happiness to Latium.
Turnus, out on the battlefield, hears the cries from the city and wants to go investigate. But Juturna, still disguised as his chariot-driver, tells him that others can defend the city while he continues to kill Trojans. Turnus tells Juturna that he's seen through her disguise, and, like his many dead friends, he'd rather die a worthy man like his ancestors than flee like a coward. Just then, Saces, a messenger, tells him that Lavinium is in bad shape and Amata has killed herself. Turnus, full of shame and anger, is determined to duel Aeneas. He rushes to the city.
Turnus's desire to prove himself a worthy descendent of his great ancestors shows that he too is pious and brave. But it's rare to see any character going against what their guardian god wants. Juno and Juturna have come together to save him—and he rejects their help. He accepts before they do that he can't keep avoiding fate. He knows he's heading for his death.
Aeneas halts the assault on the city when he hears that Turnus is coming. The armies gather around to watch the duel. The two men start with spears, then fight with swords. They fight like bulls, aiming to kill. Jove places their fates on his scales—tentatively balanced for now. Turnus powerfully strikes Aeneas, but his sword breaks. It wasn't his father's Vulcan-made, Styx-treated blade after all, but the one belonging to his charioteer. Turnus runs to try to find his sword.
Aeneas has a rather unfair advantage, since a mortal-made sword will never be able to get through his Vulcan-made shield. Though earlier we learn that Turnus seems weaker than Aeneas, when it comes to their duel, they're evenly matched—just this difference of equipment causes Turnus's problem.
Aeneas chases Turnus, like a hunting dog chasing a deer. Aeneas pauses to try to pull his spear out of an olive tree stump, not knowing that the olive tree (which the Trojans had cut down) had been sacred to Faunus, a nature god worshipped by the Latins. Turnus prays to Faunus to keep the spear stuck, and Aeneas can't wrench it free. Meanwhile, Juturna gives Turnus back his spear—but Venus, finding Juturna's helpfulness unfair, releases Aeneas's spear.
Back in Book 4, Virgil compared Dido to a wounded deer. Now he uses it again. Though the circumstances are different, the implication is the same, as the hunter is built to kill, while the deer can only run. Turnus, like Dido, has no hope of actually defeating the "hunter" Aeneas. Meanwhile, the intervening gods negate each other.
Jove asks Juno when this will all end, and what hope she still has. They both know that Aeneas is fated to win. So why bother to get Turnus back his sword? He tells her that she's given the Trojans enough grief. Finally, Juno agrees to yield. But she asks that the Latins keep their old name and customs, instead of becoming Trojans. Jove agrees, saying that the Latin-Trojan race will bring untold glory to Juno.
As if in response to Virgil's rhetorical question earlier in Book 12 about whether Jove likes seeing all this slaughter, Jove asks Juno when she'll stop all this, since, at bottom, this is all her fault. And, in the moment we've been waiting for, she gives in to fate and agrees to give up.
Jove sends down a Fury, a goddess of vengeance, to make Juturna cease helping Turnus. The Fury comes down to Turnus disguised as a bird, and Juturna understands what it means. She wishes she weren't immortal, because she wants to stay with Turnus in the underworld.
Juturna's wish to stay with Turnus recalls the many others who have wished to die along with those they love—aligning Turnus with other beloved characters who died in the Aenied, like Pallas and Anchises.
Aeneas asks Turnus why he's dawdling. Turnus says he fears Jove, not Aeneas. Turnus picks up a boulder that would be hard for a dozen men to carry, and tries to throw it at Aeneas. But he can't throw it hard enough because the Fury weakens him and slows his instincts.
This might be the most tragic moment of piety in the entire poem. Turnus is right, in general, to fear the gods more than humans—but in just this one case, Aeneas will decide Turnus's end, not Jove.
Aeneas then strikes Turnus with his spear. On his knees, Turnus reaches up to Aeneas. He asks Aeneas to pity Daunus, his father, and spare him so he can return to his people. He admits defeat and concedes Lavinia. He tells Aeneas, "Go no further down the road of hatred."
Aeneas considers Turnus's pleas, but then he sees Pallas's belt that Turnus had removed and wears as a trophy. Aeneas's feelings of mercy change to fury, and he proclaims that Pallas is the one killing Turnus. He plunges his sword into Turnus's heart, and Turnus's soul flies to the Underworld.
The ending showcases Aeneas's total pious devotion to his friend—a bond so deep that vengeance is more important than mercy. But in avenging Pallas, he fails at the Romans' unique skill, to know how to make peace, not just war. The sudden ending, with no falling action whatsoever, leaves no chance to untangle the complex morals of Aeneas's final action. Though Aeneas has finally fulfilled his fate, the Aeneid ends in anger, not joy, a fact that has caused much discussion and debate among critics.