Titus Livius (Livy), The History of Rome, Book 22
D. Spillan, A.M., M.D., Cyrus Evans, Ed.

45. While time is thus consumed in altercation rather than deliberating, Hannibal, who had kept his troops drawn up in order of battle till late in the day, [2??] when he had led the rest of them back into the camp, sends Numidians across the river to attack a watering party of the Romans from the lesser camp. [3] Having routed this disorderly band by shouting and tumult, before they had well reached the opposite bank, they advanced [p. 815]even to an outpost which was before the rampart, and near the very gates of the camp. [4] It seemed so great an indignity, that now even the camp of the Romans should be terrified by a tumultuary band of auxiliaries, that this cause alone kept back the Romans from crossing the river forthwith, and forming their line, that the chief command was on that day held by Paulus. [5] Accordingly Varro, on the following day, on which it was his turn to hold the command, without consulting his colleague, displayed the signal for battle, and forming his troops, led them across the river. Paulus followed, because he could better disapprove of the proceeding, than withhold his assistance. [6] Having crossed the river, they add to their forces those which they had in the lesser camp; and thus forming their line, place the Roman cavalry in the right wing, which was next the river; and next them the infantry: at the extremity of the left wing the allied cavalry; [7] within them the allied infantry, extending to the centre, and contiguous to the Roman legions. The darters, and the rest of the light-armed auxiliaries, formed the van. The consuls commanded the wings; Terentius the left, Aemilius the right. [8] To Geminus Servilius was committed the charge of maintaining the battle in the centre.