264 BC · Strait of Messina, Sicily Theater

Rome's intervention in Sicily began when the Mamertines — Italian mercenaries who had seized the city of Messana — appealed to Rome for protection against Syracuse and a Carthaginian garrison already inside the city. Rome crossed the Strait of Messina, expelled the Carthaginian force, and defeated a combined Syracusan-Carthaginian army. This seemingly small intervention triggered the First Punic War — the first time Roman armies had fought outside the Italian peninsula. Neither Rome nor Carthage had intended a major war; neither could afford to back down.

260 BC · Off Mylae, northern Sicily Theater

Rome, a land power with almost no naval tradition, built a fleet of 120 warships from scratch in just 60 days, reportedly copying the design of a Carthaginian quinquereme that had run aground. Rome's tactical innovation was the 'corvus' — a spiked boarding bridge that could be dropped onto an enemy ship to allow legionaries to fight a land battle at sea. At Mylae, the corvus transformed the engagement from a naval contest into an infantry melee. Rome sank or captured 50 Carthaginian ships. Duilius erected a column of captured ships' prows in the Forum — the Columna Rostrata — still partially preserved in Rome.

256 BC · Off Cape Ecnomus, southern Sicily Theater

The Battle of Cape Ecnomus may have been the largest naval battle in ancient history by number of combatants — perhaps 700 ships and 290,000 men engaged. Rome launched an invasion of Africa to strike at Carthage itself; Carthage committed its entire fleet to stop the crossing. The Carthaginians attempted to split the Roman formation, but Roman boarding tactics again proved decisive. Carthage lost some 94 ships sunk or captured; Rome lost only 24. The way to Africa was open.

255 BC · Near Tunis, North Africa (modern Tunisia) Theater

The Roman invasion of Africa went disastrously wrong. Consul Regulus, left with 15,000 men to winter near Carthage, faced a Carthaginian army reinforced by the Spartan mercenary general Xanthippus, who retrained the Carthaginian forces in Hellenistic combined-arms tactics. Xanthippus deployed war elephants on the flanks and Carthaginian cavalry in a double envelopment. The Roman infantry, crammed into a narrow front, were trampled by elephants and surrounded. Regulus was captured; only 2,000 Romans escaped. The invasion collapsed.

December 218 BC · Trebia River, northern Italy (Cisalpine Gaul) Theater

Hannibal's army had just completed the legendary crossing of the Alps — losing perhaps half its force to cold, starvation, and ambush — yet struck immediately. He lured the Roman consul Sempronius into crossing the icy Trebia River on a freezing December morning by using Numidian cavalry to raid the Roman camp. The legions crossed the river hungry, cold, and wet. Hannibal's brother Mago, hidden with 1,000 cavalry and infantry in the reed beds along the bank, burst from ambush into the Roman rear. The double envelopment was almost complete; only the Roman centre, fighting its way through the Carthaginian line, escaped. Some 20,000 Romans died.

June 217 BC · Lake Trasimene, Etruria (central Italy) Theater

Hannibal set the greatest ambush in military history. He concealed his entire army of 40,000 men in the hills and woods along a narrow lakeside road shrouded in morning mist. The Roman army of four legions marched unknowing into the trap; when the signal was given, Carthaginians poured down on three sides simultaneously. The Romans had no room to form a battle line. The consul Flaminius was killed early in the fighting. The battle lasted perhaps three hours; 15,000 Romans died in the trap, 10,000 more were captured. A Roman cavalry force of 4,000 that arrived too late was also surrounded and forced to surrender. An earthquake struck during the battle — no one noticed.

August 2, 216 BC · Cannae, Apulia (southeastern Italy) Theater

Rome committed 86,000 soldiers — the largest army it had ever put in the field — to crush Hannibal once and for all. Hannibal deployed 50,000 men with the weak Gauls and Spaniards in the centre, forming a convex bulge toward the Romans. As the Roman mass pushed forward and the centre retreated, it curved inward around the advancing legions. At the precisely right moment, Hannibal's African veterans on the flanks wheeled inward, and the heavy cavalry — having routed the Roman horse — returned to complete the encirclement. The Romans were so tightly packed they could barely raise their shields. Between 50,000 and 70,000 Romans died; perhaps 4,000 Carthaginians.

207 BC · Metaurus River, Umbria (central Italy) Theater

Hasdrubal Barca led a second Carthaginian army over the Alps to reinforce his brother Hannibal in southern Italy. Two Roman consular armies, deployed separately to block Hannibal and watch the passes, used interior lines to unite before Hasdrubal knew he faced both. At the Metaurus River, Hasdrubal found his left flank unable to negotiate broken ground; Nero made a bold march around the Carthaginian rear and struck from behind. Hasdrubal, seeing the battle was lost, charged into the Roman ranks and died fighting. His severed head was thrown into Hannibal's camp. Hannibal understood immediately: the war was lost.

October 202 BC · Near Zama, North Africa (modern Tunisia) Theater

The greatest military minds of their age met in a single battle that would decide the fate of the ancient Mediterranean. Scipio had studied Hannibal's tactics for years and had developed counters for each. He opened lanes in his formation for Hannibal's 80 war elephants to pass through harmlessly; his Numidian cavalry — the same type that had won Cannae for Carthage — pursued Carthaginian horse off the field then returned to envelop Hannibal's veteran last-reserve line. The Roman and Carthaginian infantry fought to near-exhaustion before Scipio's cavalry struck the Carthaginian rear. It was Cannae in reverse. Some 20,000 Carthaginians died; 20,000 more were captured. Hannibal escaped.

149–146 BC · Carthage, North Africa (modern Tunisia) Theater

Rome's final war against Carthage was driven not by any military threat but by the paranoid insistence of Cato the Elder, who ended every Senate speech with 'Carthage must be destroyed.' Rome manufactured a pretext, stripped Carthage of its army and weapons, then demanded the Carthaginians abandon their city entirely and resettle ten miles from the sea. Carthage refused and fought. For three years the city of half a million defended itself. In 146 BC, Scipio Aemilianus broke through the harbour defences and fought street by street for six days. The 50,000 survivors were enslaved. The city was razed to its foundations and, according to later legend, the earth was salted so nothing would grow. Scipio reportedly wept over the ruins, quoting Homer: all cities must fall.