The Battle of Lake Trasimene (24 April 217 BC, on the Julian calendar) was a major battle in the Second Punic War. The Carthaginians under Hannibal defeated the Romans under the consul Gaius Flaminius. Hannibal’s victory over the Roman army at Lake Trasimene remains, in terms of the number of men involved, the largest ambush in military history. In the prelude to the battle, Hannibal also achieved the earliest known example of a strategic turning movement.
The Carthaginian cavalry and infantry swept down from their concealed positions in the surrounding hills, blocked the road and engaged the unsuspecting Romans from three sides.
Surprised and outmanoeuvred, the Romans did not have time to draw up in battle array, and were forced to fight a desperate hand-to-hand battle in open order. The Romans were quickly split into three parts. The westernmost was attacked by the Carthaginian cavalry and forced into the lake, leaving the other two groups with no way to retreat. The centre, including Flaminius, stood its ground, but was cut down by Hannibal’s Gauls after three hours of heavy combat.
As described by Livy:
“For almost three hours the fighting went on; everywhere a desperate struggle was kept up, but it raged with greater fierceness round the consul. He was followed by the pick of his army, and wherever he saw his men hard pressed and in difficulties he at once went to their help. Distinguished by his armour he was the object of the enemy’s fiercest attacks, which his comrades did their utmost to repel, until an Insubrian horseman who knew the consul by sight – his name was Ducarius – cried out to his countrymen, “Here is the man who slew our legions and laid waste our city and our lands! I will offer him in sacrifice to the shades of my foully murdered countrymen.” Digging spurs into his horse he charged into the dense masses of the enemy, and slew an armour-bearer who threw himself in the way as he galloped up lance in rest, and then plunged his lance into the consul (Livy 22.6)”
In less than four hours, most of the Roman troops were killed. The Roman advance guard saw little combat and, once the disaster to their rear became obvious, fought their way through the skirmishers and out of the forest. Of the initial Roman force of about 30,000, about 15,000 were either killed in battle or drowned while trying to escape into the lake — including Flaminius himself, who was slain by the Gaul Ducarius. Another 10,000 are reported to have made their way back to Rome by various means, and the rest were captured.
The disaster for Rome did not end there. Within a day or two, a reinforcement force of 4,000 under the propraetor Gaius Centenius was intercepted and destroyed.