Second Punic War: Battle of the Trebia

Hannibal of Carthage
Hannibal. Public Domain

The Battle of the Trebia is believed to have been fought on December 18, 218 BC during the early stages of the Second Punic War (218-201 BC). For the second time in less than fifty years, the competing interests of Carthage and Rome came into conflict and resulted in war. Following his capture of Saguntum in Iberia, the noted Carthaginian commander Hannibal, advanced over the Alps and invaded Italy.

Taking the Romans by surprise, he advanced through the Po Valley and won a minor victory at Ticinus. A short time later, Hannibal descended on a larger Roman force along the Trebia River. Taking advantage of a rash Roman commander, he won a crushing victory. The triumph at Trebia was the first of several that Hannibal would win during his time in Italy.


Having lost Sicily after the First Punic War (264-241 BC), Carthage later endured the loss of Sardinia and Corsica to the Romans when they were distracted putting down rebellions in North Africa. Recovering from these reverses, Carthage commenced expanding its influence to the Iberian Peninsula which gave it access to a variety of resources. This expansion led to direct conflict with Rome over the Hellenized city of Saguntum which was aligned with the Italian nation. Following the assassination of pro-Carthage citizens in Saguntum, Carthaginian forces under Hannibal laid siege to the city in 219 BC.

Hannibal Marches

The city's fall after a prolonged siege led to open warfare between Rome and Carthage. Completing the capture of Saguntum, Hannibal began planning to cross the Alps to invade northern Italy. Moving forward in the spring of 218 BC, Hannibal was able to sweep aside those native tribes that attempted to block his path and entered the mountains. Battling harsh weather and rough terrain, Carthaginian forces succeeded in crossing the Alps, but lost a significant part of there numbers in the process.

Surprising the Romans by appearing in the Po Valley, Hannibal was able to earn the support of rebelling Gallic tribes in the area. Moving quickly, Roman consul Publius Cornelius Scipio attempted to block Hannibal at Ticinus in November 218 BC. Defeated and wounded in the action, Scipio was forced to fall back to Placentia and cede the plain of Lombardy to the Carthaginians. Though Hannibal's victory was minor, it had significant political repercussions as it led to additional Gauls and Ligurians joining his forces which raised his army's numbers to around 40,000 (Map).

Rome Responds

Concerned by Scipio's defeat, the Romans ordered Consul Tiberius Sempronius Longus to reinforce the position at Placentia. Alerted to Sempronius' approach, Hannibal sought to destroy the second Roman army before it could unite with Scipio, but was unable to do so as his supply situation dictated that he assault Clastidium. Reaching Scipio's camp near the banks of the Trebia River, Sempronius assumed command of the combined force. A rash and impetuous leader, Sempronius began making plans to engage Hannibal in open battle before the more senior Scipio recovered and resumed command.

Hannibal's Plans

Aware of the personality differences between the two Roman commanders, Hannibal sought to fight Sempronius rather the wilier Scipio. Establishing a camp across the Trebia from the Romans, Hannibal detached 2,000 men, led by his brother Mago, under the cover of darkness on December 17/18.

Sending them to the south, they concealed themselves in stream beds and swamps on the flanks of the two armies. The following morning, Hannibal ordered elements of his cavalry to cross the Trebia and harass the Romans. Once engaged they were to retreat and lure the Romans to a point where Mago's men could launch an ambush.

Fast Facts: Battle of the Trebia

  • Conflict: Second Punic War (218-201 BC)
  • Dates: December 18, 218 BC
  • Armies & Commanders:
    • Carthage
      • Hannibal
      • 20,000 infantry, 10,000 cavalry
    • Rome
      • Tiberius Sempronius Longus
      • 36,000 infantry, 4,000 cavalry
  • Casualties:
    • Carthage: 4,000-5,000 casualties
    • Rome: up to 26,000-32,000 killed, wounded, and captured

Hannibal Victorious

Ordering his own cavalry to attack the approaching Carthaginian horsemen, Sempronius raised his entire army and sent it forward against Hannibal's camp. Seeing this, Hannibal quickly formed his army with infantry in the center and cavalry and war elephants on the flanks. Sempronius approached in the standard Roman formation with three lines of infantry in the center and cavalry on the flanks. In addition, velite skirmishers were deployed forward. As the two armies collided, the velites were thrown back and the heavy infantry engaged (Map).

On the flanks, the Carthaginian cavalry, making use of their greater numbers, slowly pushed back their Roman counterparts. As pressure on the Roman cavalry grew, the flanks of the infantry became unprotected and open to attack. Sending forward his war elephants against the Roman left, Hannibal next ordered his cavalry to attack the exposed flanks of the Roman infantry. With the Roman lines wavering, Mago's men sprang from their concealed position and attacked Sempronius' rear. Nearly surrounded, the Roman army collapsed and began fleeing back across the river.


As the Roman army broke, thousands were cut down or trampled as they attempted to escape to safety. Only the center of Sempronius' infantry, which had fought well, was able to retire to Placentia in good order. As with many battles in this period, precise casualties are not known. Sources indicate that Carthaginian losses were around 4,000-5,000, while the Romans may have suffered up to 32,000 killed, wounded, and captured.

The victory at Trebia was Hannibal's first great triumph in Italy and would be followed by others at Lake Trasimene (217 BC) and Cannae (216 BC). Despite these stunning victories, Hannibal was never able to completely defeat Rome, and was ultimately recalled to Carthage to aid in protecting the city from a Roman army. In the resulting battle at Zama (202 BC), he was beaten and Carthage was forced to make peace.

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Hickman, Kennedy. "Second Punic War: Battle of the Trebia." ThoughtCo, Aug. 26, 2020, Hickman, Kennedy. (2020, August 26). Second Punic War: Battle of the Trebia. Retrieved from Hickman, Kennedy. "Second Punic War: Battle of the Trebia." ThoughtCo. (accessed June 8, 2023).