 Hasdrubal led the Spanish and Celtic cavalry on the left (south near the Aufidus river) of the Carthaginian army.Hasdrubal was given about 6,500 cavalry, and Hanno had 3,500 Numidians.Hasdrubal's force was able to quickly destroy the Roman cavalry (on the south), pass the Romans' infantry rear, and reach the Roman allied cavalry while they were engaged with Hanno's Numidians.