Battle of Lake Trasimene: Hannibal's Carthaginians Ambush, Defeat Romans

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Battle of Lake Trasimene: Hannibal's Carthaginians Ambush, Defeat Romans

Map of western Mediterranean, showing lands of Carthage (purple) and the Roman Republic (red)
(Unless noted otherwise, all illustrations are courtesy of Wikipedia)

Today in Military History: June 21, 217 BC

The Second Punic War (218-201 BC) provides the backdrop for today's military history tale. The expanding Roman Republic provoked a second conflict with Carthage, the commercial and military juggernaut of the western Mediterranean.


By the late 3rd century BC, Rome was the master of most of the Italian peninsula short of the Po River valley. After triumphing in the First Punic War (264-241 BC), the republic acquired the islands of Corsica, Sardinia, and Sicily. Rome was attempting to expand its influence westward along the Mediterranean coast, gaining commercial advantages in the Greek seaport of Massillia (modern-day Marseilles). At the same time, Carthage began to conquer the Celtic-Iberian tribes of Iberia (modern-day Spain). Soon, Roman political influence was filtering into Iberia, where some cities sought to throw off the Carthaginian yoke.

The war began in 218 a year after the city of Saguntum was besieged by Carthage. The Saguntines had made an alliance with Rome, then asked the Senate for assistance. The Romans sent the equivalent of a "strongly-worded statement" to the Carthaginian Senate but received no reply. After the city fell to the attackers, most of the populace chose to commit suicide rather than live under Carthaginian rule. Shortly afterwards, Rome sent a delegation of older, experienced senators to Carthage, seeking a diplomatic solution to the problem, but none could be found.

The Roman senators made one last attempt to reach a settlement with the Carthaginian Senate. According to the first century BC Roman historian Livy, Roman senator Quintus Fabius gathered a fold of his toga to his chest and offered it, saying "Here, we bring you peace and war. Take which you will." The Carthaginian senators replied "Whichever you please - we do not care." Fabius let the fold drop and proclaimed "We give you war." The senators shouted "We accept it; and in the same spirit we will fight it to the end." Therefore, war was declared.

Hannibal, son of Hamilcar Barca (247-182 BC)
Hannibal, son of Hamilcar Barca (247-182 BC)

Leading the Carthaginian army was Hannibal, today regarded as one of the finest generals of antiquity, along with Alexander the Great and Pyrrhus of Epirus. After the humiliation of the First Punic War, the Carthaginian navy was a shadow of its former self. Therefore, Hannibal followed a strategy – developed by his father – of making an overland offensive into Italy to confront Rome in its own backyard.

Carthaginian spearman, Punic Wars (Illustration coutesy of
Carthaginian spearman, Punic Wars
(Illustration coutesy of

Hannibal assembled an army which included native Carthaginian and Libyan spearmen, Iberian heavy infantry, Balearic slingers, Libyo-Carthaginian medium cavalry, and Numidian light horsemen. One unique unit in their army was the war elephant. These were a now-extinct breed of African elephants used mainly for psychological warfare to frighten the enemy, creating gaps in their lines that the Carthaginian infantry or cavalry could exploit.

After leaving the Carthaginian city of Carthago Nova (now Cartagena), Hannibal's army march along the Mediterranean coast, recruiting Iberian tribesmen along the way. Making its way into Gaul (France), Hannibal began accepting Gallic tribesmen as reinforcements. By the time the Carthaginians reached the Rhône River, his army numbered some 38,000 heavy infantry, 8000 slingers and light infantry, 8000 cavalry and 37 elephants. The Carthaginians fought a sharp battle with a local Gallic tribe with Roman sympathies, and continued its journey.

'Hannibal Crossing the Rhône,' engraving by Aaron Martinet (1836) (Illustration courtesy of New York Public Library collection)
"Hannibal Crossing the Rhône," engraving by Aaron Martinet (1836)
(Illustration courtesy of New York Public Library collection)

Hannibal in Italy

Hannibal's army eventually came to the Alps, a forbidding range of mountains that were not easily crossed. The Carthaginians crossed the Alps in late fall, battled some harassment from local Gallic tribes, and emerged onto the plains of northern Italy in early November of 218. Assessing his strength, Hannibal found his army was now composed of 20,000 heavy infantry, perhaps 6000 light infantry, 4000-6000 horsemen and 20-25 of his war elephants. He spent some time resting his men and recruiting Gallic reinforcements, then began making his plans for attacking Rome itself.

The news of Hannibal's accomplishment took Rome completely by surprise, causing a panic. They had taken no precautions to safeguard Italy itself, having recently sent two armies to oppose the Carthaginians as they journeyed from Iberia. Recruitment of new legions commenced quickly. There was a Roman army camped just south of the Po River, which quickly swung into action as news of the Carthaginian invasion reached it.

A small Roman reconnaissance force was defeated by Carthaginian cavalry at the River Ticinus. This battle was followed a month later – around the winter solstice of 218 – by a larger battle at the Trebbia River. Though effectively outnumbered, Hannibal took advantage of newly-recruited, untrained Roman soldiers and their impetuous commander to win a decisive victory. [The Carthaginians spent the remainder of the winter and early spring reprovisioning, recruiting allies from the north Italian Gallic tribes, and making attempts to break the treaties between Rome and its allied cities. It was also during this time period that most of the Carthaginian elephants succumbed to the cold north Italian winter.]

Gallic infantry recruited by Hannibal (Illustration courtesy of
Gallic infantry recruited by Hannibal
(Illustration courtesy of

The news of the disastrous Trebbia battle threw the Senate and populace of Rome into a momentary frenzy of dread, as they expected the Carthaginian army to appear at the gates of Rome any day. The Romans still had the equivalent of 7.5 legions in the field, scattered from Iberia to southern Gaul to Sicily. At the beginning of the new year of 217, the election of consuls occurred, placing Gneaus Servilius Geminus and Gaius Flaminius on the proverbial hot seats. The Senate gave both men the command of two armies badly cut up at the Ticinus andTrebbia rivers. In addition, recruitment of Romans and allied auxiliaries was stepped up. By mid-spring, four new legions were formed.

After taking command of his new army, Flaminius determined – rather than risk losing a battle to the Carthaginians – to march south to set up a defense against the invaders that was closer to Rome itself. He set up camp near the town of Arretium, and waited for the Carthaginians to appear. Hannibal's army marched south as well, at first following then passing the Romans. Hannibal then began a series of hit-and-run attacks in the countryside of Apulia, one of the main areas of Roman influence.

At first, Flaminius refused to budge from his camp. Then, as Carthaginian raids increased – according to second century BC Greek historian Polybius – "then Flaminius became … enraged at the idea that he was despised by the enemy: and as the devastation of the country went on, and he saw from the smoke that rose in every direction that the work of destruction was proceeding, he could not patiently endure the sight." Unwittingly, Flaminius was exactly where Hannibal wanted him.

The Battle of Lake Trasimene

Battle of Lake Trasimene, June 21, 217 BC (Map courtesy of Wikipedia & the Department of Military History, U.S. Military Academy)
Battle of Lake Trasimene, June 21, 217 BC
(Map courtesy of Wikipedia & the Department of Military History, U.S. Military Academy)

Hannibal was certain of the route that Flaminius would lead his 40,000 men. The Roman commander was anticipating reinforcements from the army under his fellow consul Geminus. A road ran around the northern shore of nearby Lake Tresimene, in western Umbria. Carthaginian reconnaissance had determined that the hilly, forested terrain was perfect for an ambush. Therefore, Hannibal set up his forces carefully.

The Carthaginian general set up his main camp just off the road near a narrow defile at the northeastern portion of the lake. Hannibal deployed his Spanish and African infantry as an initial blocking force. To the extreme northwest of the lake he stationed his cavalry and Gallic infantry, where a wooded valley offered a perfect platform to cut off the Romans' retreat. Then, between the two contingents, Hannibal placed his slingers and light infantry. As an added bit of subterfuge, Hannibal sent a number of his light troops off further to the east and south. They then lit large fires on several hilltops, seeking to convince Flaminius that his enemy's army was farther away.

Early the next morning, the Roman army broke camp and began marching along the lakeside road. It was a very foggy morning, with limited visibility. To compound his problems, Flaminius failed to send out any scouts to scope out the upcoming terrain. He also drove his men mercilessly, seeking to make contact with the Carthaginians as quickly as possible.

Hannibal sent a small skirmish force – probably some slingers and javelinmen – to goad the vanguard of the Roman force into advancing further. This action had the added consequence of splitting the vanguard even further from the balance of the Roman force. Then, the Carthaginian cavalry and the Gallic infantry charged from their concealment, cutting off a possible retreat route. Finally, with a blast of trumpets a general advance of the entire Carthaginian army was ordered. The slaughter commenced…

Lake Trasimene today, showing the likely site of the battle of 217 BC
Lake Trasimene today, showing the likely site of the battle of 217 BC

The attack was so well coordinated and sudden that the Romans were unable to quickly realign themselves from marching column to their normal battle formation. As a result, the legionaries were forced to fight hundred of little open formation battles. The early morning mists did not help matters, nor the fact that the narrow road abutted onto heavily forested hills, which concealed the Carthaginians until they were nearly right in the faces of the Romans.

The Romans were split into three roughly equal groups. The rearmost portion was attacked by the Carthaginian cavalry and the barbaric Gauls. The Romans were pushed off the road into the lake; those Romans not killed drowned. The center of the Roman force, under the direct command of Flaminius, managed to hold off the rampaging enemy for nearly three hours, until they were annihilated. Amazingly, the vanguard of the Roman army managed to organize themselves sufficiently to cut their way through the light infantry and skirmishers trying to block their way. After less than four hours, the battle of Lake Trasimene ended with a Carthaginian victory.


The historians Polybius and Livy recorded that about 10,000 Romans and allies managed to survive the Carthaginian ambush. At least 15,000 Romans were killed in the battle or drowned trying to escape. About 6000 Romans managed to escape through the fog, but were caught the next day. The Carthaginian commander offered them safe passage if they would surrender their weapons and armor. After doing so, however, the Carthaginians took them prisoner and the Romans soldiers were sold as slaves. Any Roman allies among them were sent back to their hometowns; Hannibal hope to destroy the system of alliances the Romans had created with allied and conquered towns. The Carthaginians then sold the confiscated equipment to merchants, who sold the armor and weapons back to the Romans.

Carthaginian losses were reported at 2500 killed with several hundred more men dying of their wounds in the weeks to come. Hannibal and his army were now the masters of central Italy. Rome was panic-stricken and expecting the enemy at its gates any moment.

'Ducarius Decapitates Flaminius at the Battle of Lake Trasimene;' - Oil on canvas painting by Joseph-Noël Sylvestre (1882)
"Ducarius Decapitates Flaminius at the Battle of Lake Trasimene;"
Oil on canvas painting by Joseph-Noël Sylvestre (1882)

Footnote #1: As a result of this loss, the Roman Senate appointed Quintus Fabius Maximus Verrucosus Cunctator as dictator. This office gave him wide executive and military powers for one year. During that time, he declared that Roman forces would avoid pitched conflict with the Carthaginians, relying instead on low-level harassment to wear the invader down, until Rome could rebuild its military strength. For most of his year in office, the strategy kept Hannibal's men from extensive foraging.

Footnote #2: At the end of Fabius's term of office, two new consuls were elected who decided to confront the Carthaginians more boldly. As a result, the disastrous battle of Cannae took place in 216, and again Rome feared for its life. Though no longer in power, Fabius posted guards at all the gates of Rome to stop its citizens from deserting the city. He walked the streets of Rome, assured as to eventual Roman victory, in an attempt to comfort his fellow Romans. Without his support, the Senate might have remained too scared to even meet.

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