What was the Battle of Lake Trasimene (217 BC)?


The Battle of Lake Trasimene was fought when a Carthaginian force under Hannibal ambushed a Roman army commanded by Gaius Flaminius on 21 June 217 BC, during the Second Punic War (218-201 BC).

It took place on the north shore of Lake Trasimene, to the east of Cortona, and resulted in a heavy defeat for the Romans. The First Punic War between Carthage and Rome ended in 241 BC after 23 years. In 219 BC the quasi-monarchial, autonomous ruler of the Carthaginian territories in south-east Iberia, Hannibal, besieged, captured and sacked the Roman protected town of Saguntum. The following spring Rome declared war on Carthage and Hannibal left Iberia for Italy with a major military expedition. Crossing the Alps Hannibal arrived in Cisalpine Gaul (northern Italy) in autumn 218 BC. The Romans rushed reinforcements north from Sicily and the Carthaginians engaged and defeated the combined Roman army at the Battle of the Trebia.

Next spring the Romans positioned two armies, one on each side of the Apennines. The Carthaginians crossed the mountains by a difficult but unguarded route and so surprised the Romans. The Carthaginians moved south into Etruria, plundering, razing the villages and small towns and killing all adult males encountered. Flaminius, in charge of the nearest Roman army, set off in pursuit. Hannibal arranged an ambush on the north shore of Lake Trasimene and trapped the Romans; killing or capturing all 25,000 of them. Several days later the Carthaginians wiped out the entire cavalry contingent of the other Roman army. The ambush and destruction of one army by another is widely considered a unique occurrence.

The Carthaginians continued their march through Etruria, then Umbria to the Adriatic coast; continuing their devastation and plundering of the territory they crossed and the killing of any adult males captured. The Carthaginian soldiers accumulated so much booty they had to cease looting because they could not carry any more. The army then marched south into Apulia, in the hope of winning over some of the ethnic Greek and Italic city states of southern Italy. News of the defeat caused a panic in Rome. Quintus Fabius Maximus Verrucosus was elected dictator and adopted the “Fabian strategy” of avoiding pitched conflict, relying instead on low-level harassment to wear the invader down, until Rome could rebuild its military strength. Next year the Romans elected Lucius Aemilius Paullus and Gaius Terentius Varro as consuls. These more aggressive commanders offered battle to Hannibal, who accepted and won a victory at Cannae which Richard Miles describes as “Rome’s greatest military disaster”. Subsequently the Carthaginians campaigned in southern Italy for a further 13 years.



Refer to First Punic War (264-241 BC), Barcid Conquest of Hispania (237-218 BC), and Siege of Saguntum (291 BC).

The First Punic War was fought between Carthage and Rome: the two main powers of the western Mediterranean in the 3rd century BC struggled for supremacy primarily on the Mediterranean island of Sicily and its surrounding waters, and also in North Africa. The war lasted for 23 years, from 264 to 241 BC, until the Carthaginians were defeated. The Treaty of Lutatius was signed by which Carthage evacuated Sicily and paid an indemnity of 3,200 talents over ten years. Four years later Rome seized Sardinia and Corsica on a cynical pretence and imposed a further 1,200 talent indemnity. The seizure of Sardinia and Corsica by Rome and the additional indemnity fuelled resentment in Carthage. Polybius considered this act of bad faith by the Romans to be the single greatest cause of war with Carthage breaking out again nineteen years later.

Shortly after Rome’s breach of the treaty the leading Carthaginian general Hamilcar Barca led many of his veterans on an expedition to expand Carthaginian holdings in south-east Iberia (modern Spain and Portugal); this was to become a quasi-monarchial, autonomous Barcid fiefdom. Carthage gained silver mines, agricultural wealth, manpower, military facilities such as shipyards and territorial depth; which encouraged it to stand up to future Roman demands. Hamilcar ruled as a viceroy and was succeeded by his son-in-law, Hasdrubal, in the early 220s BC and then his son, Hannibal, in 221 BC. In 226 BC the Ebro Treaty was agreed, specifying the Ebro River as the northern boundary of the Carthaginian sphere of influence. A little later Rome made a separate treaty of association with the city of Saguntum, well south of the Ebro. In 218 BC a Carthaginian army under Hannibal besieged, captured and sacked Saguntum. In spring 219 BC Rome declared war on Carthage.

War in Cisalpine Gaul

It was the long-standing Roman procedure to elect two men each year, known as consuls, to each lead an army. In 218 BC the Romans raised an army to campaign in Iberia under the consul Publius Scipio, who was accompanied by his brother Gnaeus. The major Gallic tribes in Cisalpine Gaul (modern northern Italy), antagonised by the founding of several Roman settlements on traditionally Gallic territory, attacked the Romans, capturing several towns. They repeatedly ambushed a Roman relief force and blockaded it in Tannetum. The Roman Senate detached one Roman and one allied legion from the force intended for Iberia to send to the region.

Carthage Invades Italy

Meanwhile, Hannibal assembled a Carthaginian army in New Carthage (modern Cartagena) over the winter, marching north in May 218 BC he entered Gaul to the east of the Pyrenees, then took an inland route to avoid the Roman allies along the coast. Hannibal left his brother Hasdrubal Barca in charge of Carthaginian interests in Iberia. The Carthaginians crossed the Alps with 38,000 infantry and 8,000 cavalry in October, surmounting the difficulties of climate, terrain and the guerrilla tactics of the native tribes.

Hannibal arrived with 20,000 infantry, 6,000 cavalry and an unknown number of elephants – the survivors of the 37 with which he left Iberia – in Cisalpine Gaul (present Piedmont) in northern Italy. The Romans had already withdrawn to their winter quarters and were astonished by Hannibal’s appearance. The Carthaginians needed to obtain supplies of food, as they had exhausted theirs on their journey, and obtain allies among the north-Italian Gallic tribes from which they could recruit, in order to build up their army to a size which would enable it to effectively take on the Romans. The local tribe, the Taurini, were unwelcoming, so Hannibal promptly besieged their capital, (near the site of modern Turin) stormed it, massacred the population and seized the supplies there. The modern historian Richard Miles believes that with these brutal actions Hannibal was sending out a clear message to the other Gallic tribes as to the likely consequences of non-cooperation.

The Romans went on the attack against the reduced force which had survived the rigours of the march and Publius Scipio personally led the cavalry and light infantry of the army he commanded against the Carthaginian cavalry at the Battle of Ticinus. He was soundly beaten and personally wounded. The Romans retreated to near Placentia, fortified their camp and awaited reinforcement. The Roman army in Sicily under Sempronius Longus was redeployed to the north and joined with Scipio’s force. After a day of heavy skirmishing in which the Romans gained the upper hand, Sempronius was eager for a battle.

Numidian cavalry lured Sempronius out of his camp and onto ground of Hannibal’s choosing, where the Battle of the Trebia took place. Fresh Carthaginian cavalry routed the outnumbered Roman cavalry, and Carthaginian light infantry outflanked the Roman infantry. A previously hidden Carthaginian force attacked the Roman infantry in the rear. Most of the Roman units then collapsed and most Romans were killed or captured by the Carthaginians, but 10,000 under Sempronius maintained formation and fought their way out to the safety of Placentia. Recognising the Carthaginians as the dominant force in Cisalpine Gaul, Gallic recruits flocked to them and their army grew to 60,000.

When news of the defeat reached Rome it initially caused panic. But this calmed once Sempronius arrived, to preside over the consular elections in the usual manner. Gnaeus Servilius Geminus and Gaius Flaminius were selected and Sempronius then returned to Placentia to see out his term to 15 March. The Carthaginian cavalry isolated both Placentia and Cremona, but these could be supplied by boat up the Po. The consuls-elect recruited further legions, both Roman and from Rome’s Latin allies; reinforced Sardinia and Sicily against the possibility of Carthaginian raids or invasion; placed garrisons at Tarentum and other places for similar reasons; built a fleet of 60 quinqueremes; and established supply depots at Ariminum and Arretium in Etruria in preparation for marching north later in the year. Two armies – of four legions each, two Roman and two allied, but with stronger than usual cavalry contingents – were formed. One was stationed at Arretium, and one on the Adriatic coast; they would be able to block Hannibal’s possible advance into central Italy, and be well positioned to move north to operate in Cisalpine Gaul. In spite of their losses, the Romans fielded twenty two legions in 217 BC, ten more than in 218 BC.

According to Polybius, the Carthaginians were now recognised as the dominant force in Cisalpine Gaul and most of the Gallic tribes sent plentiful supplies and recruits to his camp. Livy, however, claims the Carthaginians suffered from a shortage of food throughout the winter. In Polybius’s account there were only minor operations during the winter and most of the surviving Romans were evacuated down the Po and assigned to one of the two new armies being formed, while the flow of Gallic support for the Carthaginians became a flood and their army grew to 60,000. Livy retails dramatic accounts of winter confrontations, but Goldsworthy describes these as “probably an invention”.


In spring 217 BC, probably early May, the Carthaginians crossed the Apennines unopposed, taking a difficult but unguarded route and so surprising the Romans. The Carthaginians moved south into Etruria, plundering the plentiful stocks of food and looting, razing the villages and small towns and killing out of hand all adult males encountered. Hannibal learnt that one Roman army was at Arretium and was eager to bring it to battle, before it could be reinforced: Hannibal surmised the Romans would have another army on the east coast.

Once he learnt that he had been bypassed, Flaminius, the commander of the Roman army at Arrentium, set off in pursuit. Goldsworthy points out that as they passed through territory devastated by the Carthaginians there would have been a feeling of military failure and humiliation – the army existed in order to protect its homeland – and that the small farmers of the legions and their landowner officers would have taken this despoliation as an intense provocation. The Romans gained the impression, possibly fostered by Hannibal, that the Carthaginians were fleeing south before them, and according to Polybius anticipated an easy victory. The Romans were pursuing so rapidly they were unable to carry out proper reconnaissance, but they closed to less than a day’s march behind their opponents. The Carthaginians bypassed the Roman-garrisoned city of Cortona and on 20 June marched along the shore of Lake Trasimene. Hannibal decided this was a suitable spot to turn and fight.

Opposing Forces


Most male Roman citizens were eligible for military service and would serve as infantry, a better-off minority providing a cavalry component. Traditionally, when at war the Romans would raise two legions, each of 4,200 infantry and 300 cavalry. Approximately 1,200 of the infantry, poorer or younger men unable to afford the armour and equipment of a standard legionary, served as javelin-armed skirmishers, known as velites; they carried several javelins, which would be thrown from a distance, a short sword, and a 90 centimetres (3 ft) shield. The balance were equipped as heavy infantry, with body armour, a large shield and short thrusting swords. They were divided into three ranks, of which the front rank also carried two javelins, while the second and third ranks had a thrusting spear instead. Both legionary sub-units and individual legionaries fought in relatively open order. An army was usually formed by combining a Roman legion with a similarly sized and equipped legion provided by their Latin allies; allied legions usually had a larger attached complement of cavalry than Roman ones.

At Lake Trasimene the Romans fielded four legions – two Roman and two made up of allies – for a total of approximately 25,000 men.


Carthage usually recruited foreigners to make up its army. Many would be from North Africa which provided several types of fighters including: close-order infantry equipped with large shields, helmets, short swords and long thrusting spears; javelin-armed light infantry skirmishers; close-order shock cavalry (also known as “heavy cavalry“) carrying spears; and light cavalry skirmishers who threw javelins from a distance and avoided close combat. Both Iberia and Gaul provided experienced infantry; unarmoured troops who would charge ferociously, but had a reputation for breaking off if a combat was protracted. Most of the Carthaginian infantry would fight in a tightly packed formation known as a phalanx, usually forming two or three lines. Specialist slingers were recruited from the Balearic Islands.

The numbers fielded by the Carthaginians are not known, but an approximation can be made. Hannibal had arrived in Italy with 20,000 infantry and 6,000 cavalry, and had fought at the Trebia in December 218 BC with 31,000 and 11,000 respectively. In 216 BC at Cannae the Carthaginians, not having been reinforced since crossing the Apennines, had 40,000 infantry and 10,000 cavalry; it is usually assumed that more than this fought at Lake Trasimene. In any event, the Carthaginian army was considerably larger than the Roman.


Setting the Ambush

The shoreline has changed since, but at the time of the battle the road led along the north shore of the lake, then turned south, still along the lakeshore, before climbing away from the lake through a defile. To the north of the road were a range of low hills which came closer to the lake towards the east, and the defile, steadily reducing the open ground between them and the lake. The Carthaginians made camp where the hills were closest to the lake, near the defile. This was clearly visible to the Romans.

Once it was dark, Hannibal sent the various components of his army on night marches behind the hills to the north of the lake to take up positions from which they could ambush the Roman army. Night marches are notoriously difficult and often result in units becoming lost in the dark or alerting their enemy. The Carthaginians avoided both of these and took up positions on the reverse slopes of the hills. The Carthaginian cavalry were positioned furthest to the west, the north Italian Gallic infantry to their east and the experienced African and Iberian infantry furthest east, relatively close to their camp. Modern historians place the bulk of the large number of Carthaginian light infantry either around the defile and its mouth or as reinforcing the Gauls in the centre of the Carthaginian line.

On the morning of 21 June the Romans set off very early and marched eastward along the northern edge of the lake. Ancient accounts state that a thick morning mist near the lake limited visibility, but some modern historians have suggested that this was either invented or exaggerated to excuse the Romans subsequent unreadiness for battle. As Flaminius was expecting battle, the Romans probably marched in three parallel columns, which was their habit prior to a battle as this was relatively quicker to wheel into a battle line compared with a single line of march. This swiftness was relative, as forming an army up in battle order was a complicated affair which would take several hours under any circumstances. The Romans would have had a screen of light infantry out to their front and, to a lesser extent, their flank, as skirmishing was usual before a battle with the armies’ respective light troops shielding their close order colleagues while they formed up. However, Flaminius did not send out cavalry scouts to make a more distant reconnaissance; this was not unusual, Roman armies of the time rarely did so.

Springing the Trap

The leading Romans made contact with the most easterly of the Carthaginians, probably some of the African or Iberian close-order infantry, and the signal was given for all of the Carthaginians to advance, possibly by the sounding of trumpets. According to some ancient accounts the Romans could hear these signals on their flank and to their rear, but could not see their enemy, which caused confusion. It would have taken several hours for the Romans to convert their formation into a battle array, even this had been facing the direction expected. As it was, with the Carthaginians attacking unexpectedly from the flank and the rear, possibly with poor visibility, there was no chance to form even a rudimentary fighting line. Some Romans fled, others clustered into groups of various sizes, ready to engage the enemy on all sides. The fugitives and many of the impromptu Roman groups were rapidly cut down or captured. Other groups of Romans put up a stiff fight; especially in the centre, where the attacking Gauls suffered heavy casualties before beating down the trapped Romans after three hours of heavy combat.

According to Polybius, Flaminius was completely surprised and provided no effective leadership; Livy, who otherwise paints a poor picture of him, records that Flaminius was active and valiant in attempting to rally his army and organise a defence before being cut down by a Gaul. The trapped portion of the Roman army collapsed. Men attempted to swim across the lake and drowned; others waded out until the water was up to their necks, and the Carthaginian cavalrymen swam their horses out to chop at the exposed heads.

The trap failed to close on the 6,000 Romans at the front of the column, who were possibly also the Romans most prepared for battle, and they pushed their way out of the defile against little opposition. Realising that they could not affect the battle behind them, they marched on. Later in the day they were surrounded by pursuing Carthaginians and surrendered to Maharbal on the promise of being disarmed and freed; “with a garment apiece” according to Livy. However, Hannibal disapproved and only applied this to the allied captives while selling the Romans into slavery. Many of the Carthaginian infantry, especially the Libyans, equipped themselves with captured Roman armour.


The ancient sources are unclear as to the fate of the approximately 25,000 Romans known to have been engaged. According to the contemporary annalist and senator Fabius Pictor 15,000 were killed and 10,000 scattered. Polybius has 15,000 killed and most of the rest captured. Polybius reports losses of 1,500 killed for the Carthaginians, most of them Gauls; while Livy gives 2,500 killed and “many” who died of their wounds.

Follow Up

The second Roman army, originally positioned on the Adriatic coast and commanded by Gnaeus Geminus, had been marching west, intending to join up with Flaminius. Unaware that the destruction of Flaminius’s army had left the Carthaginians able to manoeuvre freely, Geminus’s entire cavalry force of 4,000 was scouting ahead when it was surprised by the Carthaginians a few days after Trasimene. Nearly 2,000 were killed in the first clash; the balance were surrounded and captured the next day. Geminus withdrew his infantry back to Ariminum (modern Rimini) on the Adriatic.


According to the modern military historian Basil Liddell Hart, Hannibal had successfully planned and executed “the greatest ambush in history.” The ambush and destruction of one army by another is widely considered a unique occurrence, with military historian Theodore Dodge commenting, “It is the only instance in history of lying in ambush with the whole of a large army.” Similarly, historian Robert O’Connell writes, “[It was] the only time an entire large army was effectively swallowed and destroyed by such a maneuver.” The historian Toni Ñaco del Hoyo describes the Battle of Lake Trasimene as one of the three “great military calamities” suffered by the Romans in the first three years of the war (The others being the Trebia and Cannae).

Aftermath and Legacy

The prisoners were badly treated if they were Romans; the Latin allies who were captured were well treated by the Carthaginians and many were freed and sent back to their cities, in the hope that they would speak well of Carthaginian martial prowess and of their treatment. Hannibal hoped some of these allies could be persuaded to defect. The Carthaginians continued their march through Etruria, then Umbria, to the Adriatic coast; continuing their devastation and plundering of the territory they crossed and the killing of any adult males captured; the Gauls were especially brutal in this respect. Contemporary reports claim that the Carthaginian soldiers accumulated so much booty they had to cease looting because they could not carry any more. The army then marched south into Apulia, in the hope of winning over some of the ethnic Greek and Italic city states of southern Italy.

News of the defeat caused a panic in Rome. Quintus Fabius Maximus Verrucosus was elected dictator by the Roman Assembly and adopted the “Fabian strategy” of avoiding pitched conflict, relying instead on low-level harassment to wear the invader down, until Rome could rebuild its military strength. Hannibal was left largely free to ravage Apulia for the next year, until the Romans ended the dictatorship and elected Paullus and Varro as consuls. These more aggressive commanders offered battle to Hannibal, who accepted and won a victory at Cannae which Richard Miles describes as “Rome’s greatest military disaster”. Subsequently the Carthaginians campaigned in southern Italy for a further 13 years.

In 204 BC Publius Cornelius Scipio, the son of the Scipio who had been wounded at Ticinus, invaded the Carthaginian homeland and defeated the Carthaginians in two major battles and won the allegiance of the Numidian kingdoms of North Africa. Hannibal and the remnants of his army were recalled from Italy to confront him. They met at the Battle of Zama in October 202 BC and Hannibal was decisively defeated. As a consequence Carthage agreed a peace treaty which stripped it of most of its territory and power.

Primary Sources

The main source for almost every aspect of the Punic Wars is the historian Polybius (c. 200 – c. 118 BC), a Greek general sent to Rome in 167 BC as a hostage. His works include a now-lost manual on military tactics, but he is now known for The Histories, written sometime after 146 BC. Polybius’s work is considered broadly objective and largely neutral as between Carthaginian and Roman points of view. Polybius was an analytical historian and wherever possible personally interviewed participants, from both sides, in the events he wrote about. The accuracy of Polybius’s account has been much debated over the past 150 years, but the modern consensus is to accept it largely at face value, and the details of the battle in modern sources are largely based on interpretations of Polybius’s account. The modern historian Andrew Curry sees Polybius as being “fairly reliable”; while Craige Champion describes him as “a remarkably well-informed, industrious, and insightful historian”.

Livy, who relied heavily on Polybius, is the other major source for this battle and the events around it. The classicist Adrian Goldsworthy considers Livy’s “reliability is often suspect”, especially with regard to his descriptions of battles, and he is generally considered untrustworthy by modern historians. Other, later, ancient accounts of the battle exist, although often in fragmentary or summary form. Modern historians usually take into account the writings of various Roman annalists, some contemporary; the Sicilian Greek Diodorus Siculus; Plutarch; Appian; and Dio Cassius. Other sources include coins, inscriptions, archaeological evidence and empirical evidence from reconstructions.


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