During the Second Punic War, King Philip V of Macedonia made an alliance with Hannibal against Rome. The Romans, in turn, allied themselves with the Aetolian League of Greek city-states. The cities of the league bore the brunt of the fighting on the Greek peninsula until after the Romans had defeated Hannibal in 202 B.C.E. Then the Roman legions were deployed against Macedonian phalanxes, and the Macedonians were defeated in a series of wars. Roman armies also won significant victories against the forces of the Seleucid emperors, and that empire shrank. After the Battle of Pydna in 168, the Romans deported the important Macedonian leaders to Rome and reshaped the Macedonian kingdom to their liking. In 148 B.C.E. they made Macedonia into a Roman province. Another decisive victory came in 146 B.C.E., when the Romans attacked the city of Corinth, which was part of another league of Greek city-states, the Achaean League. Just as they had at Carthage earlier that year, the Romans destroyed the city, looting it for treasure. In 133 B.C.E. the king of Pergamum bequeathed his kingdom to the Romans. The Ptolemies of Egypt retained formal control of their kingdom, but they obeyed Roman wishes in terms of trade policy.

The Romans had used the discord and disunity of the Hellenistic world to divide and conquer it. Once they had done so, they faced the formidable challenge of governing it without further warfare, which they met by establishing the first Roman provinces in the East. Declaring the Mediterranean mare nostrum, “our sea,” the Romans began to create political and administrative machinery to hold the Mediterranean together under a political system of provinces ruled by governors sent from Rome. Not all Romans were joyful over Rome’s conquest of the Mediterranean world; some considered the victory a misfortune. The historian Sallust (86–34 B.C.E.), writing from hindsight, complained that the acquisition of an empire was the beginning of Rome’s troubles: