The battle opened with attacks by the Carthaginian cavalry and elephants. The Roman cavalry, hopelessly outnumbered, were soon swept away. The Roman legionaries advanced, shouting and banging their sword hilts on their shields in an attempt to deter the elephants. Part of the Roman left overlapped the line of elephants, and they charged the infantry of the Carthaginian right, who broke and fled back to their camp, pursued by the Romans. This part of the Roman force probably consisted of Latin allies. The rest of the Roman infantry had difficulties with the elephants, who were not deterred by their noise but charged home, inflicting casualties and considerable confusion. At least some of the legionaries fought their way through the line of elephants, and attacked the Carthaginian phalanx. But they were too disordered to fight effectively and the phalanx held firm. Some units of the Carthaginian cavalry were now returning from their pursuit and started to attack or feint against the Roman rear and flanks. The Romans attempted to fight on all sides which brought their forward momentum to a halt.