The Aeneid can be divided into two halves based on the disparate subject matter of Books 1–6 (Aeneas's journey to Latium in Italy) and Books 7–12 (the war in Latium). These two halves are commonly regarded as reflecting Virgil's ambition to rival Homer by treating both the Odyssey's wandering theme and the Iliad's warfare themes. This is, however, a rough correspondence, the limitations of which should be borne in mind.
Journey to Italy (books 1–6)
Virgil begins his poem with a statement of his theme (Arma virumque cano ..., "Of arms and the man I sing ...") and an invocation to the Muse, falling some seven lines after the poem's inception (Musa, mihi causas memora ..., "O Muse, recount to me the causes ..."). He then explains the reason for the principal conflict in the story: the resentment held by the goddess Juno against the Trojan people. This is consistent with her role throughout the Homeric epics.
Book 1: Storm and Refuge
Also in the manner of Homer, the story proper begins in medias res (into the middle of things), with the Trojan fleet in the eastern Mediterranean, heading in the direction of Italy. The fleet, led by Aeneas, is on a voyage to find a second home. It has been foretold that in Italy he will give rise to a race both noble and courageous, a race which will become known to all nations. Juno is wrathful, because she had not been chosen in the judgment of Paris, and because her favorite city, Carthage, will be destroyed by Aeneas's descendants. Also, Ganymede, a Trojan prince, was chosen to be the cupbearer to her husband, Jupiter—replacing Juno's daughter, Hebe. Juno proceeds to Aeolus, King of the Winds, and asks that he release the winds to stir up a storm in exchange for a bribe (Deiopea, the loveliest of all her sea nymphs, as a wife). Aeolus agrees to carry out Juno's orders (line 77, "My task is / To fulfill your commands"); the storm then devastates the fleet.
Neptune takes notice: although he himself is no friend of the Trojans, he is infuriated by Juno's intrusion into his domain, and stills the winds and calms the waters, after making sure that the winds would not bother the Trojans again, lest they be punished more harshly than they were this time. The fleet takes shelter on the coast of Africa, where Aeneas rouses the spirits of his men, reassuring them that they have been through worse situations before. There, Aeneas's mother, Venus, in the form of a huntress very similar to the goddess Diana, encourages him and recounts to him the history of Carthage. Eventually, Aeneas ventures into the city, and in the temple of Juno he seeks and gains the favor of Dido, queen of the city. The city has only recently been founded by refugees from Tyre and will later become a great imperial rival and enemy to Rome.
Meanwhile, Venus has her own plans. She goes to her son, Aeneas's half-brother Cupid, and tells him to imitate Ascanius (the son of Aeneas and his first wife Creusa). Thus disguised, Cupid goes to Dido and offers the gifts expected from a guest. As Dido cradles the boy during a banquet given in honour of the Trojans, Cupid secretly weakens her sworn fidelity to the soul of her late husband Sychaeus, who was murdered by her brother Pygmalion back in Tyre, by inciting fresh love for Aeneas.
Book 2: The Trojan Horse and the Sack of Troy
In books 2 and 3, Aeneas recounts to Dido the events that occasioned the Trojans' arrival. He begins the tale shortly after the war described in the Iliad. Cunning Ulysses devised a way for Greek warriors to gain entry into the walled city of Troy by hiding in a large wooden horse. The Greeks pretended to sail away, leaving a warrior, Sinon, to mislead the Trojans into believing that the horse was an offering and that if it were taken into the city, the Trojans would be able to conquer Greece. The Trojan priest Laocoön saw through the Greek plot and urged the horse's destruction, but his protests fell on deaf ears, so he hurled his spear at the horse. Then, in what would be seen by the Trojans as punishment from the gods, two serpents emerged from the sea and devoured Laocoön, along with his two sons. The Trojans then took the horse inside the fortified walls, and after nightfall the armed Greeks emerged from it, opening the city's gates to allow the returned Greek army to slaughter the Trojans.
In a dream, Hector, the fallen Trojan prince, advised Aeneas to flee with his family. Aeneas awoke and saw with horror what was happening to his beloved city. At first he tried to fight the enemy, but soon he lost his comrades and was left alone to fend off the Greeks. He witnessed the murder of Priam by Achilles' son Pyrrhus. His mother, Venus, appeared to him and led him back to his house. Aeneas tells of his escape with his son, Ascanius, his wife Creusa, and his father, Anchises, after the occurrence of various omens (Ascanius' head catching fire without his being harmed, a clap of thunder and a shooting star). At the city gates, they notice they lost Creusa, and Aeneas goes back into the city to look for her. He only encounters her ghost, who tells him that his destiny is to reach Hesperia, where kingship and a royal spouse await him.
Book 3: Wanderings
Aeneas continues his account to Dido by telling how, rallying the other survivors, he built a fleet of ships and made landfall at various locations in the Mediterranean: Thrace, where they find the last remains of a fellow Trojan, Polydorus; Crete, which they believe to be the land where they are to build their city, which they name Pergamea (but they are set straight by Apollo); the Strophades, where they encounter the Harpy Celaeno, who tells them to leave her island and to look for Italy; and Buthrotum. This last city had been built in an attempt to replicate Troy. In Buthrotum, Aeneas meets Andromache, the widow of Hector. She is still lamenting the loss of her valiant husband and beloved child. There, too, Aeneas sees and meets Helenus, one of Priam's sons, who has the gift of prophecy. Through him, Aeneas learns the destiny laid out for him: he is divinely advised to seek out the land of Italy (also known as Ausonia or Hesperia), where his descendants will not only prosper, but in time rule the entire known world. In addition, Helenus also bids him go to the Sibyl in Cumae.
Heading into the open sea, Aeneas leaves Buthrotum, rounds the south eastern tip of Italy and makes his way towards Sicily (Trinacria). There, they are caught in the whirlpool of Charybdis and driven out to sea. Soon they come ashore at the land of the Cyclopes. There they meet a Greek, Achaemenides, one of Ulysses' men, who has been left behind when his comrades escaped the cave of Polyphemus. They take Achaemenides on board and narrowly escape Polyphemus. Shortly after, at Drepanum, Aeneas' father Anchises dies of old age. Aeneas heads on (towards Italy) and gets deflected to Carthage (by the storm described in book 1). Here, Aeneas ends his account of his wanderings to Dido.
Book 4: Fate of Queen Dido
Dido realises that she has fallen in love with Aeneas. Juno seizes upon this opportunity to make a deal with Venus, Aeneas's mother, with the intention of distracting Aeneas from his destiny of founding a city in Italy. Aeneas is inclined to return Dido's love, and during a hunting expedition, a storm drives them into a small covered grove in which Aeneas and Dido presumably made love, an event that Dido takes to indicate a marriage between them. But when Jupiter sends Mercury to remind Aeneas of his duty, he has no choice but to part. At the behest of Mercury's apparition, he leaves clandestinely at night. Her heart broken, Dido commits suicide by stabbing herself upon a pyre with Aeneas's sword. Before dying, she predicts eternal strife between Aeneas's people and hers; "rise up from my bones, avenging spirit" (4.625, trans. Fitzgerald) is a possible invocation to Hannibal.
Book 5: Sicily
Looking back from the deck of his ship, Aeneas sees the smoke of Dido's funeral pyre, and although he does not understand the exact reason behind it, he understands it as a bad omen, considering the angry madness of her love.
Hindered by bad weather from reaching Italy, the Trojans return to where they started at the beginning of book 1. Book 5 then takes place on Sicily and centers on the funeral games that Aeneas organises for the anniversary of his father's death. Aeneas organises celebratory games for the men—a boat race, a foot race, a boxing match, and an archery contest. In all those contests, Aeneas is careful to reward winners and losers, showing his leadership qualities by not allowing antagonism even after foul play. Each of these contests comments on past events or prefigures future events: the boxing match, for instance, is "a preview of the final encounter of Aeneas and Turnus", and the dove, the target during the archery contest, is connected to the deaths of Polites and King Priam in Book 2 and that of Camilla in Book 11. Afterwards, Ascanius leads the boys in a military parade and mock battle, the Lusus Troiae - a tradition he will teach the Latins while building the walls of Alba Longa.
During these events, Juno incites the Trojan women to burn the fleet and prevent the Trojans from ever reaching Italy, but her plan is thwarted when Ascanius and Aeneas intervene. Aeneas prays to Jupiter to quench the fires, which the god does with a torrential rainstorm. An anxious Aeneas is comforted by a vision of his father, who tells him to go to the underworld to receive a vision of his and Rome's future. In return for safe passage to Italy, the gods, by order of Jupiter, will receive one of Aeneas's men as a sacrifice: Palinurus, who steers Aeneas's ship by night, is put to sleep by Somnus and falls overboard.
Book 6: Underworld
Aeneas, with the guidance of the Cumaean Sibyl, descends into the underworld. They pass by crowds of the dead by the banks of the river Acheron and are ferried across by Charon before passing by Cerberus, the three-headed guardian of the underworld. Then Aeneas is shown the fates of the wicked in Tartarus and is warned by the Sibyl to bow to the justice of the gods. He also meets the shade of Dido, who remains unreconcilable. He is then brought to green fields of Elysium. There he speaks with the spirit of his father and is offered a prophetic vision of the destiny of Rome.
War in Italy (books 7–12)
Book 7: Arrival in Latium and Outbreak of War
Upon returning to the land of the living, Aeneas leads the Trojans to settle in Latium, where King Latinus received oracles pointing towards the arrival of strangers and bidding him to marry his daughter Lavinia to the foreigners, and not to Turnus, the ruler of another native people, the Rutuli. Juno, unhappy with the Trojans' favourable situation, summons the fury Alecto from the underworld to stir up a war between the Trojans and the locals. Alecto incites Amata, the Queen of Latium and the wife of Latinus, to demand that Lavinia be married to noble Turnus, and she causes Ascanius to wound a revered deer during a hunt. Hence, although Aeneas wishes to avoid a war, hostilities break out. The book closes with a catalogue of Italic warriors.
Book 8: Visit to Pallanteum, the Site of Future Rome
Given the impending war, Aeneas seeks help from the Tuscans, enemies of the Rutuli. At the place where Rome will be, he meets a friendly Greek, King Evander of Arcadia. His son Pallas agrees to join Aeneas and lead troops against the Rutuli. Venus urges her spouse Vulcan to create weapons for Aeneas, which she then presents to Aeneas as a gift. On the shield, the future history of Rome is depicted.
Book 9: Turnus' Siege of the Trojan Camp
Meanwhile, the Trojan camp is attacked by Turnus, and a midnight raid by the Trojans Nisus and Euryalus on Turnus' camp leads to their death. The next day, Turnus manages to breach the gates but is forced to retreat by jumping into the Tiber.
Book 10: The First Battle
A council of the gods is held, in which Venus and Juno speak before Jupiter, and Aeneas returns to the besieged Trojan camp accompanied by his new Arcadian and Tuscan allies. In the ensuing battle many are slain—notably Pallas, whom Evander has entrusted to Aeneas but who is killed by Turnus. Mezentius, Turnus's close associate, allows his son Lausus to be killed by Aeneas while he himself flees. He reproaches himself and faces Aeneas in single combat—an honourable but essentially futile endeavour leading to his death.
Book 11: Armistice and Battle with Camilla
After a short break in which the funeral ceremony for Pallas takes place, the war continues. Another notable native, Camilla, an Amazon character and virgin devoted to Diana, fights bravely but is killed, falling prey to her greed for gold. Arruns, the man who kills her, is struck dead by Diana's sentinel, Opis.
Book 12: Final Battle and Duel of Aeneas and Turnus
Single combat is proposed between Aeneas and Turnus, but Aeneas is so obviously superior to Turnus that the Rutuli, urged on by Turnus's divine sister, Juturna—who in turn is instigated by Juno—break the truce. Aeneas is injured by an arrow but is soon healed with the help of his mother Venus and returns to the battle. Turnus and Aeneas dominate the battle on opposite wings, but when Aeneas makes a daring attack at the city of Latium (causing the queen of Latium to hang herself in despair), he forces Turnus into single combat once more. In the duel, Turnus's strength deserts him as he tries to hurl a rock, and Aeneas's spear goes through his thigh. As Turnus is on his knees, begging for his life, the epic ends with Aeneas first tempted to obey Turnus's pleas to spare his life, but then killing him in rage when he sees that Turnus is wearing his friend Pallas's belt over a shoulder as a trophy.