The Aeneid is an epic poem written by Virgil sometime between 29 and 19 B.C.E. In the poem, Virgil details the legend of Aeneas, a prince of Troy who escaped the sacking of the legendary city and traveled across the ocean to the Italian Peninsula. There, Aeneas and his household established a new city and a new lineage that would eventually lead to his descendants, Romulus and Remus and the founding of the Roman Empire.
The hero Aeneas was well known to the Greeks and the Romans for his adventures in Homer's The Iliad. Rome adopted much of the Greek world from their gods to their art to their literature. Virgil used a collection of tales about Aeneas' wanderings combined with his history in The Iliad to create a foundation story for Rome.
By linking the lineage of Rome's founding with the ancient city of Troy, Virgil created a story that combined epic resurgence of a fallen prince to a nation that was quickly conquering the known world. The epic relied on nationalism, strengthening the divine right of the Julio-Claudian Emperors as the true descendants of the heroes and gods of the legendary battle of Troy.
The Epic Cycle
The Aeneid is roughly 10,000 lines long and it is thought that Virgil sought to overcome a literary rival of his own in the creation of the heroic cycle. His rival? Homer. Homer's legend was secure throughout the ancient world for his epic depictions of The Iliad and The Odyssey. The established mythos was reflected in Roman art, history and games.
The first half of The Aeneid details Aeneas long journey that begins with the battle for Troy and that great city's subsequent fall to his travels to Latinum (the Italian Peninsula). Virgil adds to Aeneas' fame by including a sojourn in the underworld before founding of a new city. The second half of the cycle continues with the creation of the founding principles, war for control and establishing a bloodline that would be passed on to Romulus and Remus.
Gods and Heroes
As with all epic tales of the time, the gods involved themselves in the affairs of Aeneas including Juno (Hera) who took a violent dislike to the prince of the city she was an enemy of as well as Neptune (Poseidon) who showed Aeneas favor. Virgil's goal was to firmly establish Roman heritage with the divine as the Greeks and Trojans had done long before him. He succeeded.