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The Battle of Lake Trasimene, 217 BC: the great ambush

Military history · Second Punic War · 217 BC

By Echoes of Battle

18th century engraving of the Battle of Lake Trasimene, with Hannibal's troops on the hills attacking the Roman column trapped along the lakeshore

At a glance

CarthageHannibal
vs
Roman RepublicGaius Flaminius
Date
21 June 217 BC
Location
North shore of Lake Trasimene (Umbria, Italy)
Period
The Second Punic War
Outcome
Decisive Carthaginian victory; consul Flaminius killed
By the numbers
SideStrengthLosses
Carthage (Hannibal)About 50,000Light; perhaps 1,500 to 2,500
Rome (Flaminius)About 30,000About 15,000 killed or drowned, about 15,000 captured

Ancient figures vary; these follow the commonly cited ranges from Polybius and Livy.

Quick answer

On 21 June 217 BC Hannibal trapped a Roman army in morning mist along the shore of Lake Trasimene and annihilated it in a few hours. The consul Gaius Flaminius was killed and his army of around 30,000 was destroyed, in what is often called the largest ambush in military history.

The Battle of Lake Trasimene was the most perfect ambush of the ancient world. Hannibal led an entire Roman army into a trap it never saw coming, between the hills and the water, and destroyed it before it could even form a line of battle. This is how it happened.

After the Trebia

After his victory at the Trebia in December 218 BC, Hannibal wintered in northern Italy and, in the spring, took the hard road south across the Apennines and through the flooded marshes of the Arno, a passage so punishing that he lost an eye to infection along the way1.

Black and white photograph of a marble bust of a bearded man in a helmet
Marble bust traditionally identified as Hannibal, found at Capua and now in the National Archaeological Museum in Naples; photograph by Fratelli Alinari, about 1900. Public domain

Emerging into Etruria, he set about ravaging the rich countryside to goad the Roman consul Gaius Flaminius into battle. Flaminius, camped at Arretium, took the bait and set off in pursuit2 without waiting for the other consular army, and without sending scouts far ahead3.

The trap at the lake

Hannibal knew the ground and chose it perfectly. Along the northern shore of Lake Trasimene the road ran through a narrow strip of flat land between the steep hills and the water, opening into a plain closed off by high ground. There he laid his army in wait: his heavy infantry blocking the far exit3, his cavalry and light troops hidden in the hills along the whole length of the defile.

Engraved map of Lake Trasimene with the Carthaginian ambush positions along the hills of the northern shore
Plan of the battle on the northern shore of Lake Trasimene from a 19th century English history of Rome, marking the Gauls and cavalry in ambush, the Balearic and light troops, and the heavy infantry blocking the exit near Tuoro. British Library, no known copyright restrictions

On the morning of 21 June 217 BC a thick mist rose off the lake4. Flaminius, hurrying to catch his enemy, marched his whole army into the defile in column, strung out along the shore and blind in the fog.

The ambush

At Hannibal's signal the trap closed. His troops charged down out of the hills into the flank and rear of the Roman column before it could deploy, pinning it against the lake. In the mist and chaos the Romans could not form a proper line; they fought in isolated knots or were driven into the water.

Engraving of troops descending wooded hills toward a long column of soldiers beside a lake
The battle of Trasimene as imagined in an 18th century engraving for Dom Vincent Thuillier's French translation of Polybius: Hannibal's troops pour down from the hills onto the Roman column strung out along the lake. Paris Musées, CC0

In about three hours the army was destroyed.5 Around 15,000 Romans were killed or drowned1, among them the consul Flaminius, cut down, by tradition, by a Gaulish warrior named Ducarius4. Some 15,000 more were taken prisoner.1 It was, and remains, one of the largest ambushes ever sprung.

An entire Roman army marched into the trap and was destroyed before it could form a line.

Rome in crisis

The news of Trasimene, following so soon after the Trebia, threw Rome into crisis. With two consular armies shattered in a year and Hannibal loose in Italy, the Romans took the extraordinary step of appointing a dictator, Quintus Fabius Maximus6.

Fabius adopted a new strategy: refuse open battle, shadow Hannibal, harass his foragers and let time and Italy wear him down. It was unpopular and earned him the nickname "the Delayer," but it bought Rome time it desperately needed.

Marble statue of a Roman statesman in a toga standing on a pedestal in a garden
Quintus Fabius Maximus, the Delayer, an 18th century marble statue in the gardens of Schönbrunn Palace in Vienna. Public domain

Toward Cannae

Fabius's caution was soon abandoned by bolder men who wanted a decisive victory. The result, in 216 BC, was the catastrophe of Cannae, the worst defeat in Roman history. Only after Cannae did Rome truly learn the lesson of Trasimene, and return to the patient strategy that would, in the end, bring Hannibal down.

Frequently asked questions

Who won the Battle of Lake Trasimene?

Hannibal and Carthage won a crushing victory. A Roman army of around 30,000 was destroyed in a few hours, and the consul Flaminius was killed.

When and where was the Battle of Lake Trasimene fought?

It was fought on 21 June 217 BC on the northern shore of Lake Trasimene in Umbria, central Italy, during the Second Punic War.

Why is Lake Trasimene famous?

It is often described as the largest and most successful ambush in military history: Hannibal destroyed an entire Roman army caught in column in the mist between the hills and the lake.

How did the consul Flaminius die?

Gaius Flaminius was killed in the fighting on the shore; by tradition he was cut down by a Gaulish warrior named Ducarius.

What did Trasimene lead to?

The disaster led Rome to appoint Fabius Maximus as dictator and adopt his cautious strategy of avoiding battle, before the even greater defeat at Cannae in 216 BC.

Sources and notes

Numbered notes in the text point to the works below.

  1. Polybius, Histories, Book 3, 77 to 85. ↩ a b c
  2. J. F. Lazenby, Hannibal's War: A Military History of the Second Punic War (Aris & Phillips, 1978). ↩
  3. Encyclopaedia Britannica, “Battle of Trasimene” ↩ a b
  4. Livy, Ab Urbe Condita (History of Rome), Book 22, 1 to 8. ↩ a b
  5. Livius.org (Jona Lendering), “Lake Trasimene (217 BCE)” ↩
  6. Adrian Goldsworthy, The Fall of Carthage: The Punic Wars 265-146 BC (Cassell, 2000). ↩
  7. Wikipedia, “Battle of Lake Trasimene, Wikipedia”

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