On June 24th, 217 BC, after goading the commander of a Roman army into a rash pursuit, Carthaginian general Hannibal Barca, using deception and guile, lured them into a trap along the northern shore of Lake Trasimene. There, he sprang on his unsuspecting pursuers what is considered, in terms of the number of combatants involved, history’s largest tactical military ambush.
After Hannibal defeated two Roman armies in northern Italy in 218 BC, Rome’s consuls for 217 BC were sent at the head of two armies to deal with him. One of the consuls, Gaius Flaminius, gathered the survivors of the earlier defeats, and reinforced by new recruits, formed them into an army of about 30,000 men and marched south to defend Rome. Hannibal followed him, and marching faster, overtook and passed Flaminius, and got his own army between that of the Romans and their home city.
It was one of history’s earliest examples of a successful strategic turning movement, getting between a defender and his base. Taking advantage of that, and to draw out Flaminius and goad him into giving battle, Hannibal began devastating and burning the countryside as he marched south. Flaminius was compelled to hurry his army to catch up with Hannibal before the Carthaginian reached Rome.
As Hannibal continued his march southward, with Flaminius in hot pursuit, the Carthaginian came upon a suitable spot for an ambush at Lake Trasimene, about 80 miles north of Rome. There, a stretch of the road passed through a defile, hemmed in between the lake’s northern shore and forested hills. Hannibal set up his camp on the eastern end of the defile, so as to be within clear of sight of Flaminius when he got there.
Hannibal formed his heavy infantry in front of the camp facing the road down which the Romans would arrive, to challenge them into battle. On the forested hills skirting the road to the north, he concealed his cavalry, light infantry, and Gaulish allies, and waited. When Flaminius arrived at the defile’s entrance on the morning of June 24th and saw the Carthaginian camp with forces arrayed in front of it to offer battle, he was relieved to have finally caught up with his quarry, and unwilling to chance Hannibal’s slipping away again, immediately marched in to get at the Carthaginians.
In his eagerness, Flaminius did not scout the hills to the north of the road before marching his army into the defile, and the hidden Carthaginians’ concealment was further helped by a fortuitous fog that morning, which reduced visibility. Once the last Roman entered the defile, trumpets were blown and the trap was sprung, as the concealed forces rushed down from the hills to fall on the flank and rear of the Romans, who suddenly found themselves surrounded on east, north, and west by the enemy, while the lake blocked them to the south. Flaminius’ army was wiped out, and out of the 30,000 men he took into battle that day, about half were killed or drowned, while the other half were taken prisoner.