Punic Wars
Rome and Carthage fought three wars for mastery of the western Mediterranean. Having survived Hannibal’s invasion of Italy, Rome destroyed Carthage and took control of the Mediterranean.

Heinrich Leutemann · Public domain · Source
Having united Italy, Rome collided with Carthage, the sea power founded by the Phoenicians in North Africa. In the First Punic War (264–241 BC) Rome built a navy, won and made Sicily its first province.
In the Second Punic War (218–201 BC) the Carthaginian general Hannibal marched from Spain over the Alps into Italy with elephants. He encircled and annihilated a Roman army at Cannae in 216 BC and roamed Italy for more than fifteen years, but most of Rome’s allies stayed loyal. When Scipio carried the war to Africa, Hannibal was recalled and defeated at Zama in 202 BC. In the Third Punic War (149–146 BC) Rome razed Carthage, and in the same year it destroyed Corinth in Greece.
Rome was master of the Mediterranean, but at a cost. Small farmers were ruined by long wars while cheap grain flowed in from the provinces and great slave-run estates (latifundia) spread, widening the gap between rich and poor — the background to the Gracchan reforms and the civil wars.