Rome's great rival in this early period of expansion was the North-African city of Carthage, founded centuries earlier by Phoenician explorers. Carthage was one of the richest and most powerful trading empires of the Hellenistic Age, a peer of the Alexandrian empires to the east, trading with them and occasionally skirmishing with the Ptolemaic armies of Egypt and with the Greek cities of Sicily. Rome and Carthage had long been trading partners, and for centuries there was no real reason for them to be enemies since they were separated by the Mediterranean. That being said, as Rome’s power increased to encompass all of Italy, the Carthaginians became increasingly concerned that Rome might pose a threat to its own dominance.
Conflict finally broke out in 264 BCE in Sicily. The island of Sicily was one of the oldest and most important areas for Greek colonization. There, a war broke out between the two most powerful poleis, Syracuse and Messina. The Carthaginians sent a fleet to intervene on behalf of Messinans, but the Messinans then called for help from Rome as well (a betrayal of sorts from the perspective of Carthage). Soon, the conflict escalated as Carthage took the side of Syracuse and Rome saw an opportunity to expand Roman power in Sicily. The Centuriate Assembly voted to escalate the Roman military commitment since its members wanted the potential riches to be won in war. This initiated the First Punic War, which lasted from 264 to 241 BCE (note: “Punic” refers to the Roman term for Carthage and its civilization).
The Romans suffered several defeats, but they were rich and powerful enough at this point to persist in the war effort. Rome benefited greatly from the fact that the Carthaginians did not realize that the war could grow to be about more than just Sicily; even after winning victories there, the Carthaginians never tried to invade Italy itself (which they could have done, at least early on). The Romans eventually learned how to carry out effective naval warfare and stranded the Carthaginian army in Sicily. The Carthaginians sued for peace in 241 BCE and agreed to give up their claims to Sicily and to pay a war indemnity. The Romans, however, betrayed them and seized the islands of Corsica and Sardinia as well, territories that were still under the nominal control of Carthage.
From the aftermath of the First Punic War and the seizure of Sicily, Sardinia, and Corsica emerged the Roman provincial system: the islands were turned into “provinces” of the Republic, each of which was obligated to pay tribute (the “tithe,” meaning tenth, of all grain) and follow the orders of Roman governors appointed by the senate. That system would continue for the rest of the republican and imperial periods of Roman history, with the governors wielding enormous power and influence in their respective provinces.
Unsurprisingly, the Carthaginians wanted revenge, not just for their loss in the war but for Rome’s seizure of Corsica and Sardinia. For twenty years, the Carthaginians built up their forces and their resources, most notably by invading and conquering a large section of Spain, containing rich mines of gold and copper and thousands of Spanish Celts who came to serve as mercenaries in the Carthaginian armies. In 218 BCE, the great Carthaginian general Hannibal (son of the most successful general who had fought the Romans in the First Punic War) launched a surprise attack in Spain against Roman allies and then against Roman forces themselves. This led to the Second Punic War (218 BCE - 202 BCE).
Hannibal crossed the Alps into Italy from Spain with 60,000 men and a few dozen war elephants (most of the elephants perished, but the survivors proved very effective, and terrifying, against the Roman forces). For the next two years, he crushed every Roman army sent against him, killing tens of thousands of Roman soldiers and marching perilously close to Rome. Hannibal never lost a single battle in Italy, yet neither did he force the Romans to sue for peace.
Hannibal defeated the Romans repeatedly with clever tactics: he lured them across icy rivers and ambushed them, he concealed a whole army in the fog one morning and then sprang on a Roman legion, and he led the Romans into narrow passes and slaughtered them. In one battle in 216 BCE, Hannibal’s smaller army defeated a larger Roman force by letting it push in the Carthaginian center, then surrounding it with cavalry. He was hampered, though, by the fact that he did not have a siege train to attack Rome itself (which was heavily fortified), and he failed to win over the southern Italian peoples who had been conquered by the Romans a century earlier. The Romans kept losing to Hannibal, but they were largely successful in keeping Hannibal from receiving reinforcements from Spain and Africa, slowly but steadily weakening his forces.
Eventually, the Romans altered their tactics and launched a guerrilla war against Hannibal within Italy, harrying his forces. This was totally contrary to their usual tactics, and the dictator Fabius Maximus who insisted on it in 217 BCE was mockingly nicknamed “the Delayer” by his detractors in the Roman government despite his evident success. The Romans vacillated on this strategy, suffering the terrible defeat mentioned above in 216 BCE, but as Hannibal’s victories grew and some cities in Italy and Sicily started defecting to the Carthaginian side, they returned to it.
A brilliant Roman general named Scipio defeated the Carthaginian forces back in Spain in 207 BCE, cutting Hannibal off from both reinforcements and supplies, which weakened his army significantly. Scipio then attacked Africa itself, forcing Carthage to recall Hannibal to protect the city. Hannibal finally lost in 202 BCE after coming as close as anyone had to defeating the Romans. The victorious Scipio, now easily the most powerful man in Rome, became the first great general to add to his own name the name of the place he conquered: he became Scipio “Africanus” - conqueror of Africa.
An uneasy peace lasted for several decades between Rome and Carthage, despite enduring anti-Carthaginian hatred in Rome; one prominent senator named Cato the Elder reputedly ended every speech in the senate with the statement “…and Carthage must be destroyed.” Rome finally forced the issue in the mid-second century BCE by meddling in Carthaginian affairs. The third and last Punic War that ensued was utterly one-sided: it began in 149 BCE, and by 146 BCE Carthage was defeated. Not only were thousands of the Carthaginian people killed or enslaved, but the city itself was brutally sacked (the comment by Polybius regarding the terror inspired by Rome, noted above, was specifically in reference to the horrific sack of Carthage).