Titus Livius (Livy), The History of Rome, Book 31
Cyrus Evans, Ed.

21. The consular army had, by this time, been conducted from Arretium to Ariminum, and the five thousand Latin confederates had crossed from Gaul into Etruria. [2] Lucius Furius, therefore, advanced from Ariminum, by forced marches, against the Gauls, who were then besieging Cremona, and pitched his camp at the distance of one mile and a half from the enemy. [3] Furius had an opportunity of performing a splendid exploit, had he, without halting, led his troops directly to attack their camp; scattered hither and thither, they were wandering through the country; [4] and the guard, which they had left, was not sufficiently strong; but he was apprehensive that his men were too much fatigued by [p. 1361]their hasty march. [5] The Gauls, recalled from the fields by the shouts of their party, returned to the camp without seizing the booty within their reach, and, next day, marched out to offer battle. [6] The Roman did not decline the combat, but had scarcely time to draw up his forces, so rapidly did the enemy advance to the fight. [7] The right brigade (for he had the troops of the allies divided into brigades) was placed in the first line, the two Roman legions in reserve. Marcus Furius was at the head of the right brigade, Marcus Caecilius of the legions, and Lucius Valerius Flaccus of the cavalry: these were all lieutenant-generals. [8] Two other lieutenant-generals, Cneius Laetorius and Publius Titinnius, the praetor kept near himself, that, with their assistance, he might observe and take proper measures against all sudden attempts of the enemy. [9] At first, the Gauls, bending their whole force to one point, were in hopes of being able to overwhelm, and trample under foot, the right brigade, which was in the van; [10] but not succeeding, they endeavoured to turn round the flanks, and to surround their enemy's line, which, considering the multitude of their forces, and the small number of the others, seemed easy to be done. [11] On observing this, the praetor, in order to extend his own line, brought up the two legions from the reserve, and placed them on the right and left of the brigade which was engaged in the van; [12] vowing a temple to Jupiter, if he should rout the enemy on that day. [13] To Lucius Valerius he gave orders, to make the horsemen of the two legions on one flank, and the cavalry of the allies on the other, charge the wings of the enemy, and not suffer them to come round to his rear. [14] At the same time, observing that the centre of the line of the Gauls was weakened, from having extended the wings, he directed his men to make an attack there in close order, and to break through their ranks. [15] The wings were routed by the cavalry, and, at the same time, the centre by the foot; and suddenly, being worsted in all parts with great slaughter, the Gauls turned their backs, and fled to their camp in hurry and confusion. [16] The cavalry pursued them as they fled; and the legions, coming up in a short time after, assaulted the camp, from whence there did not escape so many as six thousand men. [17] There were slain and taken above thirty-five thousand, with seventy standards, and above two hundred Gallic waggons laden with much booty. Hamilcar, [p. 1362]the Carthaginian general, fell in that battle, and three distinguished generals of the Gauls. [18] The prisoners taken at Placentia, to the number of two thousand free-men, were restored to the colony.