Battle of the Trebia

The Battle of the Trebia, also spelled Trebbia, was the opening major clash of the Second Punic War. It was fought between Hannibal’s Carthaginians and a Roman army led by Sempronius Longus on either 22 or 23 December 218 BC. Both sides fielded roughly 40,000 men, but the Carthaginians had more cavalry while the Romans had more infantry. The fighting occurred on the floodplain west of the lower Trebia River, near the settlement of Placentia (modern Piacenza), and ended in a severe Roman defeat.

The war between Carthage and Rome began in 218 BC. In response, Hannibal marched a large army from Iberia (modern Spain and Portugal), through Gaul, across the Alps, and into Cisalpine Gaul (northern Italy). The Romans attacked the weakened force that survived the journey. At the Battle of Ticinus, Publius Scipio personally led his cavalry and light infantry against Hannibal’s horsemen, but the Romans were routed and Scipio wounded. The Romans withdrew to the area near Placentia, fortified their camp, and waited for reinforcements. The Roman army in Sicily, under Sempronius, was sent north and joined Scipio’s force. After a day of heavy skirmishing where the Romans had the advantage, Sempronius grew eager for a full battle.

Hannibal used his Numidian cavalry to trick the Romans into leaving their camp and moving onto ground he had chosen. Fresh Carthaginian horsemen then overwhelmed the outnumbered Roman cavalry, and Carthaginian light infantry attacked the Roman infantry from the flanks. A hidden Carthaginian force struck the Roman infantry from behind. Most Roman units collapsed, and the majority of the Romans were killed or captured. However, 10,000 men under Sempronius kept their formation and fought their way to safety inside Placentia. With the Carthaginians now clearly the dominant power in Cisalpine Gaul, Gallic recruits flocked to them, swelling Hannibal’s army to 60,000. The next spring, he moved south into Roman Italy and won again at Lake Trasimene. In 216 BC, he marched to southern Italy and inflicted the catastrophic defeat at Cannae—the last of what modern historians call the three great Roman calamities in the war’s first three years.

**Background**

**Pre-war** The First Punic War (264–241 BC) was fought between Carthage and Rome, the two major western Mediterranean powers, for control of Sicily and its waters, and in North Africa. After 23 years, Carthage was defeated. Five years later, the leading Carthaginian general Hamilcar Barca landed in Carthaginian Iberia (southeastern Spain). He greatly expanded this territory, turning it into a quasi-monarchical, autonomous domain for his family, the Barcids. This expansion brought Carthage silver mines, agricultural wealth, manpower, military facilities like shipyards, and strategic depth, encouraging it to resist future Roman demands. Hamilcar ruled autonomously until his death in 228 BC. His son-in-law Hasdrubal succeeded him, and in 221 BC, his son Hannibal took over. In 226 BC, the Ebro Treaty set the Ebro River as the northern limit of Carthaginian influence in Iberia. Soon after, Rome made a separate treaty with the independent city of Saguntum (modern Sagunto), far south of the Ebro. In 219 BC, Hannibal besieged, captured, and sacked Saguntum, prompting Rome to declare war.

**War in Cisalpine Gaul** Rome’s custom was to elect two senior magistrates, called consuls, each year. In wartime, each led an army. In 218 BC, the Romans raised an army for Iberia under consul Publius Scipio, accompanied by his brother Gnaeus. The major Gallic tribes in northern Italy on both sides of the Po River—known as Cisalpine Gaul—were angered by Roman colonists settling at Piacentia and Cremona earlier that year on traditional Gallic land. The Gauls rose up, captured several towns, repeatedly ambushed a Roman relief force, and blockaded it in Tannetum. The Roman Senate detached one Roman and one allied legion from the Iberian force and sent them to the region. The Scipios had to raise fresh troops to replace them, so they could not leave for Iberia until September.

**Carthage invades Italy** Meanwhile, Hannibal gathered a Carthaginian army at New Carthage (modern Cartagena) in late 219 and early 218 BC. It marched north in May 218 BC, entered Gaul east of the Pyrenees, and took an inland route to avoid Roman allies on the coast. Hannibal left his brother Hasdrubal Barca in charge of Carthaginian interests in Iberia. The Roman fleet carrying the Scipio brothers’ army landed at Rome’s ally Massalia (modern Marseille) at the mouth of the Rhone in September, around the same time Hannibal was fighting his way across that river against local Allobroges at the Battle of Rhone Crossing. A Roman cavalry patrol scattered some Carthaginian horsemen, but Hannibal’s main army evaded the Romans. Gnaeus Scipio continued to Iberia with the Roman force; Publius returned to Italy. The Carthaginians crossed the Alps with 38,000 infantry and 8,000 cavalry in October, overcoming difficulties of climate, terrain, and guerrilla attacks from native tribes. Hannibal arrived in what is now Piedmont, northern Italy, with 20,000 infantry, 6,000 cavalry, and about 30 war elephants from the force that had left Iberia. The Romans, already in winter quarters, were stunned by Hannibal’s arrival.