The armies of Rome and Carthage had established camps on either side of the river Aufidius.
The Romans crossed the river and formed up into a central block of more than 60,000 infantry soldiers flanked by cavalry.
Hannibal's army of 45,000 men crossed the river and lined up in a convex formation with cavalry on the sides. The screen of lightly armed Carthaginian troops moved behind the infantry.
The Roman infantry advanced upon that of the Carthaginians who withdrew, drawing the Romans in. The massed Roman foot soldiers became crammed together by the push of men from the rear.
The left block of the Carthaginian cavalry attacked the opposing Roman cavalry, who fled. Both Carthaginian wings fell upon the remaining Roman cavalry.
When the Roman cavalry fled, the Carthaginian cavalry attacked the Roman infantry from the rear, destroying them. This was Rome's darkest hour and Hannibal's greatest victory.
