Battle of the Trebia
The Battle of the Trebia was the first major battle of the Second Punic War, fought between the Carthaginian forces of Hannibal and the Roman Republic in December of 218 BC, on or around the winter solstice. It was a resounding Roman defeat with heavy losses, with only about 10,000 out of 40,000 Romans surviving and retreating to Placentia. In this battle, Hannibal got the better of the Romans by exercising the careful and innovative planning for which he was famous. The impetuous and short-sighted opposing general, the consul Tiberius Sempronius Longus, allowed himself to be provoked into a frontal assault under physically difficult circumstances and failed to see that he was being led into a trap.
The battle took place in the flat country of the Province of Piacenza on the left bank of the Trebbia River, a shallow, braided stream, not far south from its confluence with the Po river. The battle is named for the river. Although the precise location is not known, it is accepted as being visible from the Via Emilia, now paralleled by highway A21/E70 and a railroad trunk line, all of which come from Piacenza, a contemporaneously placed Roman colony, and cross the river north of where the Romans died in the battle. The area is possibly in the comune of Rottofreno at its main settlement, San Nicolò a Trebbia, in the vicinity of the coordinates given at the head of this article.
Prelude
Arrival of Hannibal
Hannibal began the Second Punic War in 219 BC by attacking the Roman-allied city of Saguntum just north of what is now Valencia in Spain. After destroying the city, he marched on Italy, beginning with a force of approximately 40,000 men and a few dozen war elephants when he crossed the Ebro river in Spain, the previous border between Roman and Carthaginian interests. Trekking over the Alps the Carthaginian force made it through the mountains with staggering losses, being reduced to 26,000 emaciated men. Winning a completely unequal conflict against the Ligurians and the first legion-sized battle with the Romans at the river Ticinus, he had filled out his army with Gallic and other allies to the number of 43,000 men: 32,000 infantry and 11,000 cavalry, by the time of the Battle of Trebia. They were more than enough to be completely effective against the Romans; moreover, by that time, Hannibal had turned all Gallia Cisalpina against the Romans, and the Carthaginians were prospering on enthusiastic Gallic supply and support.Hannibal maneuvers
The Roman Senate, appalled by the massacre of the Ligurians, had ordered the consul Tiberius Sempronius Longus, who was stationed in Sicily, to reinforce the existing Roman general, Publius Cornelius Scipio. Unknown to them now, Scipio had been wounded during the Battle of Ticinus and had been driven into the hills south of Piacenza, then Placentia, a contemporary colony of the Romans.Scipio had no choice but to hold himself where he was until he could be reinforced by Sempronius. At this time, Hannibal was camped in the plain below Scipio's camp near Placentia. The exact place where Hannibal camped is unclear, but it is thought to have been southeast of Placentia, on the Nura. According to Theodore Ayrault Dodge, Hannibal apparently had two objectives in mind: to accept the friendly overtures of the Gallic tribes who dwelt in the northern foothills of the Apennines and to prevent the two consuls from coming to the aid of the other.
With regard to the second objective, Dodge points out that Hannibal, astride the direct road from Ariminum, was in a centrally occupied position to potentially prevent Sempronius from joining his forces with Scipio. As a result, Dodge cites this maneuver as "one of the earliest and best instances of the taking up a central position between two armies of the enemy" and comments that Hannibal's strategic understanding had presaged Napoleon’s strategy of the central position, which he used against generals Johann Peter Beaulieu and Michelangelo Colli in the 1796 Montenotte Campaign:
Finding himself blocked from reinforcement, Scipio became distressed. Moreover, he was troubled by a defection among the Gauls in his own camp, who killed a number of the Roman men on guard. This defection, Scipio feared, was the signal of a more general insurrection, and he wished to keep his hold on the Ananes nearby, which was one of the few tribes in the vicinity which had remained loyal to Rome. This he thought he could do by camping in their midst.
Leaving a small number of troops in camp to conceal his movement, Scipio decided to move the bulk of his forces across the Trebia, wading through the chilled winter waters of the stream amid snow and rain. The Romans were discovered by a detachment of Carthaginian cavalry who sought to interrupt their march. The Romans, it is said, could scarcely lift their arms to defend themselves. Yet, while harassing the Romans, the Carthaginian cavalrymen turned aside to pillage Scipio's abandoned camp. This allowed Scipio to move his forces across the Trebia, where he took up and fortified a camp on the left bank.
Arrival of Sempronius Longus
After receiving the orders of the Senate at Lilybaeum in Sicily, Sempronius had dismissed his men after taking their oaths to reassemble at Ariminum south of the Po river. From there, he probably marched along the route of the future Via Aemilia straight into Placentia. Sempronius' two legions assembled probably in early December, and Hannibal had ascertained at an early date that Sempronius was ordered to northern Italy. Being interposed between the two consuls, he could have sought a general engagement with Scipio's army before Sempronius arrived with his forces. Yet it appears that Hannibal did not wish to defeat his opponents in detail, and as shown by subsequent events, Sempronius was allowed to link up with Scipio's army.With regard to the problem of how Sempronius coming from Ariminum could have effected Livy's union with Scipio on the Trebbia's left bank if Hannibal was on the right bank, Georg Niebuhr discards the Ariminum passage and conjectures that Sempronius came through Liguria. Regardless, it was not long before "Tiberius and his legions arrived and marched through the city." They did not stop there, probably because Hannibal's Numidian cavalry had burned the Roman fort, but camped outside it to the south, at or near Hannibal's previous camp, some 40 days after they had left Sicily. Apparently Hannibal had crossed the Trebbia in his pursuit of Scipio and was camped on its left bank.
Capture of Clastidium
Despite Gallic willingness to supply Hannibal, he found that the size of his army was becoming a burden on the local communities resulting in a "daily increasing scarcity". The Romans had a grain storage depot at Clastidium, which he was planning to attack. He must have bypassed it previously on his way to Placentia. Instead of attacking, he found that he could bribe the commander, Dasius Brundisius, whose name indicates he was not Roman but was from Brundisium, with 400 gold coins. The garrison was subsequently treated with kindness, which suggests that good treatment was part of the deal, but none of the sources describe it in detail.Clastidium was located on the right bank of the Po upstream from the Trebbia. That Hannibal could operate there without hindrance indicates that he was in fact camped on the left bank of the Trebbia and subsequent operations against the Gauls prove it further.
Dissent among the Gauls
For reasons unstated by either author, the Carthaginians suspected treachery from the Gauls located between the Trebbia and the Po; that is, on the left bank of the Trebbia, where his subsequent activity shows that Hannibal was certainly located. The authors make it clear that the Gauls hoped to stay on the good side of both commanders, but they do not give the details. Hannibal was incensed enough to dispatch 5,000 infantry and 1,000 cavalry to devastate their country, "district by district" and this action decided whose side they were to take. They appealed to the Romans.Sempronius sent an unspecified number of cavalry across the river with 1,000 infantry. They caught the Carthaginians pillaging there and drove them into Hannibal's camp. The Carthaginians acquired reinforcements and sallied out to push the Romans back across the river, where the Romans sent for reinforcements from their camp. Hannibal stopped the Carthaginian attack because this was not the time and place of his choosing, but was happening spontaneously. Sempronius, however, concluded he had won a victory with the very arm in which Scipio had been beaten, the cavalry.
Hannibal now knew that he could provoke Sempronius and made plans to entice him across the river, where his troops could be slaughtered without assistance from the camp.
The consuls confer
The cavalry action of the preceding day had inspired the Romans with confidence. Sempronius resolved to seek "a decisive battle as soon as possible". The Senate had sent him to assist Scipio, but the latter was unable to be assisted, leaving Sempronius in an ambiguous situation. According to Polybius, Sempronius felt free to act on his own: "He was, it is true, at liberty to act as he thought best owing to the illness of Scipio." Nevertheless, he felt obliged to argue it out with his colleague in heated language: "What good is there in further delay and waste of time? Where is the third consul and the third army we are waiting for?... it is from their native soil, from the land in which they were born, that the Romans are to be driven." He accuses the Romans of "cowering within their camp in the heart of Italy." Livy is unable to say, however, where this harangue took place, whether sitting "by his ailing comrade, or in the headquarters." There is no mention at all of the camp at Ripa Alta or how Scipio would have gotten to the camp near Placentia or whether Sempronius had any authority to command Scipio's men.Wherever this consultation of consuls took place, Scipio advised "that their legions would be all the better for a winter's drilling, and that the notoriously fickle Celts would not remain loyal to the Carthaginians... he advised Sempronius to let matters remain as they were." Sempronius decided to ignore Scipio and go ahead with the attack. The texts do not say that he kept Scipio informed.
Numbers
Romans
When Scipio left Massilia he had no or minimal forces. In northern Italy, he superseded Lucius Manlius, acquiring his two legions plus 10,000 allied infantry and 1,000 cavalry, and Gaius Atilius, reacquiring the legion that had been taken from him by the Senate plus 5,000 allies. Since Livy is using 4,000 infantry and 300 cavalry as the standard complement of a legion, Scipio should have had 12,000 Roman infantry and 900 Roman cavalry plus at most 13,700 allied infantry and 1,000 cavalry. After losses suffered at Ticinus, Scipio should have had at most 27,000 men.Sempronius had been given two legions: 8,000 infantry and 600 cavalry, but he also had several thousand allies, about 16,000 infantry and 1,800 cavalry. Scipio had the greater army and would have been senior in command if active. Neither consul, however, could supersede the other without a decree from the Senate.
Livy states the actual number of Roman troops before the battle to have been 18,000 men, to which were added 20,000 Italic allies. Polybius sets the number at 16,000 and 20,000 allies, "this being the strength of their complete army for decisive operations, when the consuls chance to be united." He does not say that they were united, only that, if they were, these would be their numbers; that is, 4 Roman legions and 4 allied alae. Both authors subsequently tack on 4,000 cavalry, evidently not part of the 36,000 or 38,000, from which it may be inferred that the latter were infantry.
The numbers stated to have fought the battle are problematic: a combined Roman army should have had 5 legions of 20,000 men and all 30,000 allies authorized by the Senate and yet, if the armies were not combined, Sempronius should have had only two legions of 8,000 men. One answer is that Scipio gave up two legions and kept one and 20,000 auxiliaries in his own camp as a reserve. Livy seems to think that Scipio's wound gave the entire authority to Sempronius, but immediately after the battle Scipio commanded an army marching from his camp to Placentia. If Scipio could command after the battle then he was not so incapacitated as to be removed from command before it. Both authors agreed that the two consuls had sharp differences of opinion and that Sempronius acted on his own.
It is possible that the authors doubled the number of Roman legions fighting the battle and that Sempronius had only 8,000 or 9,000 Roman infantry. The authors both relate, however, that a mass of 10,000 men broke out of the Carthaginian encirclement and fell back on Placentia. Tiberius apparently did have more than two legions. Scipio argues in the story that Sempronius' men needed the winter to train, suggesting that on the way to north Italy Sempronius may have raised two more legions of recruits, throwing them into battle under difficult physical circumstances against expert advice without training. There is no mention of any such events, however.
Yet another hypothesis for reconciling the numbers cited by Livy for combined strength of the two consular armies and the actual number of participants in the battle of the Trebia would be that Sempronius detached part of his allied contingents for garrison duty on Sicily and for naval service with Marcus Aemilius and Sextus Pomponius. Some allowance should also be made for non-combat losses. The strength of this hypothesis lies in the maximum use of ancient evidence.
The 10,000 veteran troops who did not break and run were the major survivors. The authors make it clear that not many of the others made it to Piacenza, but some did. The others were massacred, as was Hannibal's custom. They appear to have been the mysterious extra legions – perhaps recruits – the cavalry and the auxiliaries. The casualties therefore were a maximum of 32,000 men, a rate of 76%. The rate was not at maximum, but the number who escaped is not known. If it was half the number who fell back in good order, the rate would have been 64%, in either case a Roman disaster, but perhaps not quite the one depicted by the authors if Scipio's army was not involved. The Carthaginians did not cross the river to take Sempronius' camp. They might have been physically exhausted or concerned about the 10,000 or they could have been deterred by the army in the second camp on their flank.
Carthaginians
Although Hannibal departed Spain with 50,000 infantry and 9,000 cavalry his long march to Italy had clearly cost his army dearly. He had, however, been largely able to make up for his losses with new recruits from among the Cisalpine Gauls. Both sources agree that he fought the battle with 40,000 men: 20,000 Gallic, Iberian peninsular and African heavy-armed infantry, 10,000 cavalry plus another 1,000 in ambush, 8,000 Balearic slingers and spearmen plus another 1,000 in ambush. While the casualties were not stated, the square of 10,000 Roman infantry that broke the Carthaginian center caused a "great slaughter" of African and Gallic troops.Battle
Mago's ambush
The December of 218 BC was cold and snowy. Scipio was still recovering from his wounds but Sempronius was "impetuous and headstrong". Eager to come to blows with Hannibal before Scipio could recover and assume command– and especially as the time for the election of new consuls was drawing near–Sempronius took measures looking for a general engagement, disregarding Scipio's caution not to attack with untrained men. Unfortunately for Sempronius, Hannibal was aware of this, and prepared a plan to take advantage of Sempronius' impetuosity. Hannibal's force was camped across the cold and flooded Trebbia River. Polybius says,Hannibal was relying on a network of Gallic spies to keep informed of enemy activity. When they told him that the Romans were ready to do battle, he sent for 100 each of the best infantrymen and cavalrymen and had them select 10 each for a special mission. This detachment of 1,100 infantry and 1,100 cavalry under the command of Hannibal's younger brother, Mago, were instructed to conceal themselves in the underbrush of the above-mentioned water-course under the cover of night, and prepare an ambush for the Romans.
Numidian provocation
On the following morning, Hannibal sent the rest of the Numidian cavalry beyond the Trebbia to harass the nearby Roman camp and retreat, so as to lure the Romans into a position from which Mago's hidden detachment could strike at the opportune moment. They rode up to the gates and discharged missiles at the men on duty. In response, Sempronius sent out the Roman cavalry to drive them off, and shortly afterwards sent out 6,000 javelin-throwers, the light-armed infantry, to cover the formation of the main line of battle behind them. These were the 12,000 Roman heavy-armed infantry and 20,000 Italian allies, apparently heavy-armed also, as they were never used as light-armed infantry.Roman crossing of the Trebia
, a military historian, wrote of the battle:Hannibal's strengthening of flanks
Hannibal now put forward his 8,000 light infantry – javelin-throwers and Balearic slingers – as a covering skirmishing line, and behind them, he formed the main battle line of 20,000 infantry of Africans, Iberian peninsulars, and Gauls, with 10,000 cavalry and an unspecified number of elephants split between the two flanks.The Numidian cavalry wheeled suddenly and attacked the Roman cavalry, strung out in pursuit. Sempronius withdrew them to the flanks. The Numidians then harassed the Roman light infantry screen, or velites, causing them to expend all their missiles. As the armies approached they were unable to be much of an impediment to the Carthaginians due to lack of ammunition and hypothermia, so Sempronius ordered them to fall back through the heavy infantry. Similarly, when the Balearic slingers and javelin-throwers began to encounter Roman heavy infantry, Hannibal withdrew them and placed them on the wings.
Entrapment
After the light-armed infantry retreated through the Roman line, the Roman infantry closed with the Carthaginian infantry. Concurrently the Carthaginian cavalry and elephants attacked the Roman and Italian cavalry, sweeping them from the field, and leaving the infantry, whom they intended to protect, exposed. Samuels suggests that in describing the Roman cavalry as being a withdrawal he is being tactful and a rout better describes what happened. Seeing that the Roman rear had passed their position, Mago's hidden force emerged from the ambush and fell on the rear of the hard-pressed Roman infantry. With their morale already sapped by cold, hunger, and fatigue, the Romans on the sides and in the rear broke formation under this fresh onslaught and ran for the river.As the disorganized men were milling about the river, Hannibal used the opportunity to effect a massacre. The great majority of the casualties fell here or drowned in the river. The Roman cavalry escaped on horseback. As the Roman soldiers remained with Sempronius in the center and majority of the force were the 20,000 Italics, the men who died were probably not the core of the army but were on the whole the Italic allies, who were as yet untrained and untested in battle.
Roman hollow square
It is clear from the odds and from subsequent events that Tiberius intended a main attack on the center of the Carthaginian line. As he was not killed on the flanks or in the rear, he must have been commanding the center in person. It would have included his most experienced and effective infantry. In fact, they behaved as professional soldiers, some of them quickly wheeling to fill in the sides and rear, forming a hollow square. In this standard Roman infantry formation, all sides faced outward leaving the center necessarily hollow, where the command post was and where the wounded were placed. This square soon deflected all Carthaginian attacks against it. The Carthaginians concentrated on the men by the river instead.A light-infantry detachment was sent out to stop the elephants. These they dealt with by volleying darts and jabbing under the tail. The elephants became wild, attacking both sides, until Hannibal ordered them driven off to the left to attack the Gauls fighting for Rome. These must have been the Cenomani tribesmen, the only Gauls in that category. What Livy means by "the left" is not clear, but they cannot have been in the square and most perished.
Although he had made some unfortunate strategic decisions, Tiberius proved himself a better battlefield general, ordering his men forward against the Carthaginian center. The enemy there took great losses, although the authors do not say what they were. Of the two ethnic groups, Africans and Celts, the latter are said to have lost the most men. The square soon found itself at the Carthaginian rear and looking back could see the Carthaginian army effecting a slaughter of allied troops. Tiberius did not return to their assistance – the sources offer his excuses of the river and the heavy rain – but marched his men into Piacenza, probably over a bridge that must have stood where the highway and railroad bridges now stand.
Historical problems
The positions of the combatants with regard to the battlefield's topographic features are as follows. Scipio first camped before Placentia with Hannibal 50 stadia away on the right bank of the Trebbia. Then he crossed the Trebbia and marched south to camp at Ripa Alta. Hannibal camped 40 stadia away, and this was his camp during the battle. The location was probably near Gragnano Trebbiense on the Trebbia's left bank. If it had been on the right bank, Hannibal would have intercepted Sempronius and prevented him from camping near Scipio. But, that is what Sempronius did. Scipio was on the right bank; Sempronius on the left. When the Gauls came into Sempronius' camp to ask for help, Sempronius sent men across the Trebbia to drive the plunderers into Hannibal's camp.The Roman start line was between Tiberius' camp and the Trebbia. The hollow square broke out on the left bank and were "prevented by the river" from their camp, so they went on to Placentia, followed by the other survivors. The problem is that Placentia lies on the opposite bank, on the same side as the camp, so that if the river was an obstacle in reaching the camp, it must have been an obstacle in reaching Placentia north of the camp. What is worse, Livy has Scipio in the same camp as Sempronius, crossing the river to enter Piacenza on the bank he had just left.
Either Sempronius' camp was on the left bank and all the narrative of events before the battle is wrong, or the description of the retreat is wrong. Both solutions have been proposed. Mommsen simply assumed that the square did recross the river, but closer to Placentia, perhaps on a bridge. The colonists must have had bridges over both the Po and the Trebbia; however, this information has been left out of the story. If the Roman camp was on the left bank, then the early sequence is all wrong and one must presume even more information was omitted from the story.
Aftermath
Public reaction
The next night, according to Livy, "the camp garrison and the other survivors, mainly wounded men, crossed the Trebia on rafts." Scipio was in command. He "marched his army in perfect quiet to Placentia, whence he crossed the Po to Cremona, that a single colony might be spared the burden of two armies in winter quarters". In the single-camp interpretation of this passage, Scipio must have crossed to the enemy side regardless of whether the camp was on the left or right bank. However, the narrative goes on to say that Hannibal did not cross the river to pursue them; thus, as previously, Scipio was placing the river between him and Hannibal. Following the thread of the previous narrative, Scipio must still have been in his camp at Ripa Alta. Some survivors managed to make their way upriver on the same side as the battle to Scipio's camp. Scipio broke camp at night, crossed the river and reached Placentia on the right bank, past Sempronius' now abandoned camp, or perhaps picking up the garrison left there along with additional survivors. He still had an army of such magnitude that it could not seek supplies in the same city as Sempronius'.For a time, the Romans were spared attacks by the Carthaginians, as the latter were now suffering from exposure. A cold snap had set in and the precipitation had turned from rain to snow and ice. All the elephants but one died along with "many men and horses". When the news arrived at Rome that both consuls had been defeated at Ticinus and Trebbia, the population panicked, expecting to see Hannibal at the gates. In fact, the defeats were not the catastrophe they believed. More than two and a half legions escaped from the battlefield, three more under Scipio never participated, while two more were in Spain. In all, the Senate still had seven and a half legions healthy and in good winter quarters.
By now, the Carthaginians had recovered. Their cavalry isolated both cities, but these were easily supplied by boat up the Po. Sempronius evaded the enemy cavalry to return to Rome and conduct consular elections. The two new consuls elected were Gnaeus Servilius Geminus and Gaius Flaminius, the latter of whom would lead the Roman army during the debacle at Lake Trasimene. Meanwhile, they were not scheduled to assume command until 15 March, the first day of the Roman year in 217 BC. Sempronius returned immediately to his command. The new consul-elects recruited more legions of Romans and allies, reinforced Sardinia and Sicily, placed garrisons at Tarentum and other places, built a fleet of 60 quinqueremes and established supply depots at Ariminum and Arretium in Etruria in preparation for marching north. They asked for military assistance from Hiero, tyrant of Syracuse, and received 1,500 men. Flaminius marched into winter camp at Arretium and Servilius at Ariminum.
Final operations around Placentia
Sempronius had established winter posts, but he was harassed by Hannibal's Numidian cavalry accompanied by Lusitanian and Celtiberian raiders, which impeded any line of supply that did not come through the river. The Romans had constructed a fortified outpost near Placentia, Emporium, though. Hannibal decided to test it by attacking at night with cavalry and light infantry, but the sentries were alert. They raised the camp, which shouted so loudly that it could be heard in Placentia. At dawn the next morning, Sempronius' own cavalry fell upon the Carthaginians, driving them off and wounding Hannibal slightly. Of this defense, Livy uses the word "brilliant."A few days later, Hannibal marched on a supply depot at Victumulae Its population had been enhanced by anti-Carthaginian refugees from all the Gallic tribes. Untrained, they went out to meet Hannibal as a mob of 35,000 and were shortly driven back into Victumulae, which arranged a formal surrender. As soon as the garrison had turned over its weapons, Hannibal's men on signal ravaged the town, committing "every kind of outrage that lust, cruelty and brutal insolence could suggest". This may, however, be a piece of stereotyping by Livy, who was known for promoting the Carthaginians as deceitful and terrible, and also it would fit with the Gallic stereotype of being barbaric.
For a time the "cold was intolerable" but as spring began to come on Hannibal resolved to attack Etruria following the Trebbia southward. In the Apennines, the army was struck by a thunderstorm of such intensity that they could not pitch camp and when rain turned to hail and snow they put the tents flat and crawled under them. The storm was followed by a cold snap. All the elephants except one, and many of the horses died. After two days Hannibal returned to the Placentia region and camped. Sempronius, in the last of his term as consul, determined to do battle, left Placentia and camped three miles from Hannibal.
Hannibal was down to 12,000 infantry and 5,000 cavalry, perhaps not from casualties, more likely because his army, relying on Gallic allies, was seasonal. Marching the next morning to Tiberius' camp, he was met by the Romans, who drove him back on his camp and then attacked it. Putting the bulk of his men in the center, Hannibal waited for the Roman to break in, but they never managed to do so. When they began to leave at the end of the day Hannibal sallied out in force to attack the Roman rear, hoping to effect a massacre. The fall of night prevented that event. Casualties were equal on both sides. This was the last military engagement of the consular year, a year of defeats, but perhaps not disastrous, as the next year would be.
Military assessments
The assessment of the English historian Sir Walter Raleigh is:Three great errors Sempronius committed, of which every one deserved to be recompensed with the loss that followed. The first was, that he fought with Hannibal in a champain, being by far inferior in horse, and withal thereby subject to the African elephants, which in enclosed or uneven grounds, and woodlands, would have been of no use. His second error was, that he made no discovery of the place upon which he fought, whereby he was grossly overreached, and ensnared, by the ambush which Hannibal had laid for him. The third was, that he drenched his footmen with empty stomachs, in the river of Trebia, even in a most cold and frosty day, whereby in effect they lost the use of their limbs.