The Battle of the Trebia, 218 BC: Hannibal's first blow

The Trebia was Hannibal's first pitched battle on Italian soil, and it showed at once how he meant to fight: he chose the time, the place and the weather, and let his enemy's impatience do the rest.²

Background

In 218 BC Rome and Carthage went to war for the second time. The spark was Saguntum, a Spanish town allied to Rome, which Hannibal took after a siege of eight months. Instead of waiting to be attacked in Spain, Hannibal marched his army from Spain over the Pyrenees and the Alps and came down into the plains of the Po in the autumn, his army much reduced by the crossing but soon joined by Gauls of the region who hated Rome.³ › Hannibal Barca

How many men he brought over the mountains was disputed even in antiquity. Polybius, citing the figures Hannibal himself had inscribed on a column at Lacinium in southern Italy, gives 12,000 African and 8,000 Spanish infantry and no more than 6,000 horse; Livy records estimates running from about that figure up to 100,000 foot and 20,000 horse, and accepts that the march had cost Hannibal a great many men and animals.⁴

The consul Publius Cornelius Scipio met him first, in a cavalry battle near the Ticinus river. Scipio was badly wounded and fell back across the Po toward Placentia, and some of the Gauls serving in his army murdered the guards at the gates one night and deserted to Hannibal. Fearing a general revolt of the Gauls, Scipio withdrew to the hills by the Trebia, a tributary of the Po, and waited there for help.⁵

Help came from the south. The Senate recalled the other consul, Tiberius Sempronius Longus, who had been preparing an invasion of Africa from Sicily, and his army marched the length of Italy to join Scipio's camp on the Trebia.⁶

Armies and commanders

The two consuls did not agree. Scipio, still recovering from his wound, wanted to wait through the winter, drill the new legions and let the fickle Gauls tire of their Carthaginian guests. Sempronius wanted a victory, and he wanted it before Scipio recovered and before the next consuls took office. Polybius, the Greek historian who wrote the fullest account of the war, judges that he chose his own time, not the one the situation demanded.⁷

Hannibal read the situation the same way as Scipio, and so he wanted battle at once: while the Gauls were still enthusiastic, while the legions were still raw and before Scipio could take the field. Gauls who moved between both camps kept him informed, and he knew that Sempronius was rash.⁸

When a Carthaginian raid on Gaulish villages drew the Roman cavalry and light troops across the river, Sempronius won a small skirmish and grew more confident still. Hannibal recalled his men rather than be drawn into a general battle on a chance occasion.⁹

The sources give the numbers only for the day of battle. Polybius counts 16,000 Roman and 20,000 allied infantry with 4,000 cavalry; Livy 18,000 Romans and 20,000 Latin allies, besides Gaulish auxiliaries from the Cenomani. Against them Hannibal drew up some 20,000 heavy infantry of Spaniards, Gauls and Africans, about 8,000 light troops and slingers from the Balearic islands, more than 10,000 cavalry with his Gaulish allies, and his war elephants. Britannica gives modern estimates of about 30,000 Carthaginians and allies against roughly 42,000 Romans.¹⁰

The battle in phases

Between the two camps ran a watercourse with high, steep banks overgrown with brambles and marsh plants. Polybius notes that the Romans, wary of woods, did not suspect flat open ground of hiding an ambush. Hannibal rode round it himself and decided to use it.¹¹

That evening he chose a hundred cavalry and a hundred infantry, the boldest men he had, and told each of them to pick out more men like themselves from his own company. Polybius and Livy both tell the story, though Livy has each man choose nine and Polybius ten. In the night this force of 1,000 horse and 1,000 foot went into hiding in the watercourse under the command of Mago, Hannibal's young brother.¹²

At daybreak the Numidian horsemen crossed the Trebia and rode up to the Roman camp, throwing javelins at the outposts to draw the Romans out. Hannibal's other troops ate their breakfast, saw to their horses and their weapons, and waited by their fires, rubbing their bodies with oil against the cold.¹³

Sempronius took the bait. He sent out his cavalry, then about 6,000 light infantry, then the whole army, before the men had eaten. It was about the winter solstice, and the day was bitterly cold and snowy. The Trebia, swollen by rain in the night, came up to the soldiers' chests, and by the time they had crossed and formed up on the far bank they were frozen and hungry and could scarcely hold their weapons.¹⁴

The fresh Carthaginian skirmishers drove in the Roman light troops, who had spent their javelins on the Numidians. Then Hannibal's cavalry, stronger in numbers and fresher, routed the Roman horse on both wings. With the flanks of the legions bare, the light troops and the elephants fell on them from the sides.¹⁵

Turning point

In the center the heavy infantry fought for a long time on equal terms. Then Mago's men rose from the watercourse behind the Roman line and fell on its rear, and the whole Roman army was thrown into confusion.¹⁶

The Roman wings, pressed by the elephants in front and the light troops and cavalry on every side, broke and were driven back toward the river. Livy and Dodge add that the elephants, turned back by the Roman light infantry, were sent against the Gaulish auxiliaries on the Roman left and put them to flight.¹⁷

The Roman center did not break. Some 10,000 legionaries pushed straight through the Gauls and Africans in the middle of Hannibal's line. Cut off from their camp by the river and the storm, they kept together and marched away to Placentia. Most of the rest were killed near the river by the elephants and the cavalry, or drowned trying to cross it.¹⁸

Aftermath

The losses are not recorded with any precision. Polybius writes that very few Africans and Spaniards fell and that the Gauls bore most of Hannibal's losses; Britannica's modern estimate is at least 15,000 Romans dead, perhaps 12,000 to 15,000 more taken prisoner, and about 5,000 Carthaginian casualties.¹⁹

The weather took its own toll. The rain and snow that followed killed many men and horses, and nearly all of Hannibal's elephants: all but one, according to Polybius. The Carthaginians pursued only as far as the river. That night Scipio led the troops left in the Roman camp across the Trebia on rafts and away to Placentia, and from there across the Po to Cremona.²⁰

Sempronius sent word to Rome that a battle had been fought and that the storm had robbed him of the victory. Rome soon learned the truth, and the city, Livy writes, was gripped by terror; the Senate raised new legions, sent troops to Sardinia and Sicily and garrisons to the south, and prepared a fleet.²¹ › The Battle of Lake Trasimene, 217 BC

For Hannibal the greatest gain was political. The Gauls of northern Italy, who had waited to see who would win, now came over to him in numbers.²²

Legacy and memory

The Trebia was the first of the three great victories that Hannibal won in Italy in three years. In the spring he crossed the Apennines and the flooded marshes of Etruria, where an infection cost him the sight of one eye, and in 217 BC he trapped another consular army at Lake Trasimene; in 216 BC came Cannae.²³ › The Battle of Cannae, 216 BC

Ancient and modern writers drew the same lessons. Polybius praised Hannibal for refusing to fight on a chance pretext and for hiding his ambush where the Romans did not think to look. Britannica sees the battle as one of many in which Hannibal used nature, the environment and knowledge of his enemy to multiply the strength of a smaller army, and Dodge called him a master of stratagem.²⁴

Exactly where the battle was fought is still argued. Dodge, writing in 1891, concluded that no field could be fixed with certainty and placed the fighting east of the Trebia, while HistoryOfWar.org and the plan above place it on the plain west of the river.²⁵

Test yourself on Hannibal's war in the ancient battles quiz, or read on through antiquity.