So, to answer the first part of your question, the Trojan settlement of Rome is considered to be more of a myth than fact, just as probably the entire Trojan War was. The Trojans were not “Greek” or “Latin”, but most likely a Hittite group (the Hittites were the culture living in Turkey at the time).

Furthermore, according to the Aeneid (the story connecting the Romans to the Trojans), the Trojan Aeneas marries into the Latin group in Italy, and his descendants end up settling the city we now call Rome. Even according to Roman tradition, they didn’t see themselves as carrying the banner of the Trojans, but rather just honoring their heritage. Think of how Japanese-Americans felt during World War II. Did they recognize that they were of Japanese heritage? Yes, but they still felt more connected to their American culture and society.

So, why did Rome move into the Greek states? Well, the Greeks had actually settled Italy starting in the 8th century BCE. Some of the more famous cities are Tarentum, Messene, and Syracuse. Rome knew of “Greece’s” existence - Greece in quotes as the Greeks were, simply put, always fighting each other. As Rome began their conquest of Italy beginning in the 5th century BCE, they largely ignored the Greek cities in Italy as they actually admired the Greek culture. The Iliad was translated into Latin, Romans consulted the Oracle at Delphi, and the Romans adopted Greek names. However, by the 3rd century, Rome was too powerful and dominant to keep ignoring other threats on their peninsula. By 272, Tarentum had fallen, and by the end of the First Punic War in 241, Rome also controlled nearly all of Sicily (Carthage had conquered the Greek states in Sicily before Rome could make it down there).

So by that point, Rome had made its first move against Greek cities. At this point, though, its main rival in the Mediterranean was Carthage. The story of Hannibal against Rome is well-known, but what is less famous but just as significant is that Philip V of Macedon, thinking that Hannibal would emerge victorious, made an alliance with him in 215. After defeating Hannibal, Rome, in its anger, had to punish Philip and Macedon for daring to ally with Rome’s sworn enemy. In 196, Macedon relinquished its claim on the Greek city-states (Athens, Sparta, etc.) after being thoughrouly destroyed by Roman legions. Another war led by the last Macedonian king Perseus ended in complete failure in 168 at the Battle of Pydna, as the Romans completely dismantled the Macedonian kingdom and annexed it as a province. At this point, the Greek city-states pretty much accepted Roman dominion, but a final revolt led by the “pseudo-Philip” Andriskos in 146 ended with the utter destruction of the city of Corinth and the submission of the Greek states to Roman rule.

TL;DR - The Romans admired the Greeks, but had to conquer the Greek cities in Italy to cement their rule, ended up conquering more Greek cities after defeating Carthage, and moved into the Greek mainland after punishing Macedon for allying with Carthage. There was no connection to their mythical Trojan heritage.

(A thank you to Professor Emily Mackil at UC Berkeley).

Harris, W.V. 1979. War and Imperialism in Republican Rome. Oxford.

Gruen, E. 1984. The Hellenistic World and the Coming of Rome. Berkeley.

———. 1990. Studies in Greek Culture and Roman Policy. Berkeley.

Eckstein, A.M. 2006. Mediterranean Anarchy, Interstate War, and the Rise of Rome. Berkeley.

Walbank, F.W. 1957-1979. A Historical Commentary on Polybius. Oxford.