After the fall of Troy, Aeneas led a group of survivors to the Tiber River in Italy. Friction developed between the Trojans and the local inhabitants. As a result, a coalition of Italian tribes waged war against the Trojans.
Aeneas left the Trojan camp with some of his followers to forge an alliance with Evander, the king of a group of Arcadians who settled in Italy. His mission was successful. Moreover, at Evander’s suggestion, he traveled farther away from the Trojan camp to gain the alliance of the Etruscans.
While Aeneas was absent, Turnus, the king of the Rutulians, led the Italian armies against the Trojan camp. They did not accomplish anything the first day, but did a lot of damage on the second day of their campaign.
At the beginning of the tenth book of the Aeneid, the Olympian gods were discussing the situation. Jupiter objected to the war. It was his will that the Trojans settle in Latium in peace.
Venus then spoke at length. Since she was the mother of Aeneas, she favored the Trojans and vehemently inveighed against Turnus. However, her chief and most valid complaint was the activity of Juno, whose inveterate hatred had caused the Trojans many hardships, even though they had followed divine oracles when they journeyed to Italy.
Juno did not offer a satisfactory defense of her own actions, but she presented two cogent arguments. She pointed out that Turnus had a right to defend his own land. She also pointed out that Venus was expressing concern for the Trojans at the wrong time. She should have worried about them when Paris committed the crime that started the Trojan War. [This argument was especially effective since all the Olympians knew that Venus was an accomplice of Paris when he stole the wife of Menelaus.]
Some of the assembled gods approved of what Venus said, while others favored Juno. Jupiter resigned himself to the fact that war was inevitable. He decided that he would help neither side. The outcome of the war would be decided by military prowess and by Fate.
Down on earth, the Trojans were not faring well. They were trapped in their camp, but help was on the way.
The Etruscans readily agreed to ally themselves with Aeneas. They wanted to wage war on Turnus, but a soothsayer said that they would not be successful unless a foreign prince would lead them. So when the Trojan Aeneas met with them, they eagerly accepted him as their leader.
Among the Etruscan leaders who aided the Trojans were Massicus, who brought troops from Clusium and Caere; Abas, whose men came from Populonia and from the island now called Elba; and the soothsayer Asilas, who brought men from Pisa.
Another leader was Cupavo, whose father had become a swan. In that form, he flew up into the heavens and became the constellation Cygnus. In memory of his father, Cupavo wore the feathers of a swan on his helmet.
Of all the Etruscan leaders that allied themselves with Aeneas, Virgil was especially interested in Ocnus, who came from Mantua. Virgil had been born near this city.
As Aeneas and his allies were sailing to the field of battle, a group of nymphs swam up to his ship and greeted him. The nymphs used to be the ships with which the Trojans sailed from Troy to Italy. When Turnus tried to burn them, they had been miraculously transformed into beautiful water deities.
One of these nymphs was named Cymodoce. She told Aeneas what was happening at the camp and urged him to hurry back so that he could assist his beleaguered comrades.
As she was leaving, she gave the ship of Aeneas a push, so that it traveled forward at a terrific speed. To try to keep up with him, the other ships increased their speed. [According to the Theogony of Hesiod, Cymodoce is one of the daughters of Nereus. Either this is one of the many inconsistencies that occur in Greek and Roman mythology, or else there are two different nymphs named Cymodoce.]
As the besieged Trojans caught sight of Aeneas and his allies, they were filled with joy.
At the same time, Turnus reacted with vigor. After giving his men a brief pep talk, he rushed to the shore with part of his army, leaving the rest to continue the siege of the Trojan camp.
In the ensuing battle, Aeneas killed many formidable foes, even Gyas and Cisseus, the sons of Melampus, who had been an associate of Hercules. Pallas, the son of Evander, also made a daring charge against the enemy and killed many of them.
The Italians also fought valiantly. Clausus, a Sabine leader from Cures, gained many laurels. Halaesus attacked the Arcadians and killed several of their warriors. Lausus, the son of Mezentius, proved to be a formidable foe.
In the meantime, Pallas did what he could to check the Italian heroes. After encouraging his Arcadian followers, he killed Halaesus and prepared to fight with Lausus. However, Turnus arrived on the scene and loudly declared that he would engage in single combat with Pallas, so Lausus stepped aside.
Before the encounter, Pallas offered a prayer to Hercules, who had become a god after his death. He reminded Hercules that his father Evander had offered him hospitality. Hercules wanted to help Pallas, but he couldn’t. Fate had decreed that Pallas must die.
Pallas threw his spear first. It pierced the armor of Turnus and gave him a superficial wound. Then Turnus threw his javelin. It pierced the chest of Pallas. Turnus removed a splendid belt from his fallen foe and wore it himself.
Since Pallas was a close friend of Aeneas, the Trojan hero was furious. He charged into the Italian ranks, seeking Turnus and killing many as he went. He gave no quarter.
Because of the fury of Aeneas, the Italians were no longer able to besiege the Trojan camp. Ascanius and his comrades were able to leave its confines.
In the meantime, Juno was concerned about Turnus, since he would surely die if Aeneas managed to find him. Jupiter gave her permission to save Turnus, but he warned her that she would only be postponing his fate.
Juno approached the field of battle. Under her guidance, a cloud took on the appearance of Aeneas. Turnus saw the cloud and charged. The fake Aeneas ran away and jumped on one of the ships, with Turnus hot on its heels.
As soon as Turnus had boarded the ship, Juno cut the ropes, and winds carried Turnus away from the field of battle. The cloud then no longer pretended to be Aeneas, but rose up into the sky where it belonged.
Turnus realized that everyone would think that he had fled from the battlefield in a cowardly fashion. On three different occasions, he tried to jump overboard and swim to shore, so that he could rejoin his troops. He also tried to kill himself three times. Juno saw to it that he remained on the ship and stayed alive until the ship carried him safe and sound to the city where his father Daunus lived.
In the meantime, Mezentius played a prominent role in the ongoing battle. Mezentius had been an Etruscan king, but his people had deposed him because of his cruelty. Turnus had given him asylum. It was for this reason that the Etruscans hated Turnus and wanted to wage war on his kingdom.
While the Trojans were complacently enjoying their temporary success, Mezentius launched an effective attack against them. When the Etruscan allies of Aeneas saw the man whom they hated, they directed their hostilities against him alone; but their efforts proved to be futile. Mezentius was like a rock jutting out into a hostile sea, which firmly withstood all the violence of the winds and the waves.
Seeing the damage that Mezentius and his friends were doing, Aeneas rushed forward to stop them. As the fierce renegade Etruscan prepared to fight Aeneas, he promised to give his son Lausus the armor of Aeneas.
The spear of Aeneas pierced the armor of Mezentius and drew blood. As Aeneas attempted to dispatch the wounded warrior with his sword, Lausus defended his father. Mezentius was led to safety, but Aeneas killed Lausus.
In despair, the wounded Mezentius mounted Rhoebus, his faithful horse, and began to throw spears at Aeneas. Aeneas killed the horse with a javelin. The horse pinned Mezentius as it fell.
The fierce Mezentius did not bargain for his life. However, he was afraid that his former subjects would mistreat his body if it fell into their hands. He asked Aeneas to allow him to be buried with his son Lausus.
This summary is based on a version of the Latin text presented online by the Latin Library. I also consulted an offline English translation by Allen Mandelbaum.