Hannibal set his bridled cavalry in the centre, and strengthened the wings with Numidians. The battle cry had scarcely gone up when Scipio's javelin-throwers ran back amidst the supporting troops to the second line. After that there was a cavalry battle, which for some time remained even, but then the infantry became involved in the fighting and it startled the horses. Many riders were thrown from their mounts, or climbed down on seeing their comrades surrounded and under pressure, and it had become mostly a battle fought on foot, until the Numidians on the wings effected a slight encircling maneuver to appear to the rear of the Romans. At this, panic struck the Romans....
~ Livy, History of Rome, 21.46
Now Massinissa and his Numidian cavalry confronted Publuis Scipio while he was on the move, and then kept constant pressure on him day and night. Not only would he capture Romans who wandered too far from camp to gather wood and fodder, but he would ride right up to the camp and, often charging into the midst of the sentry-posts, he would cause terrible confusion everywhere. During the nights too, there was often panic at the gates, and the rampart, from his surprise attacks. There was no time and no place that the Romans could be free from fear and worry, and they were pinned down within their fortifications, deprived of access to all essentials.
~ Livy, History of Rome, 25.34