Titus Livius (Livy), The History of Rome, Book 38
Evan T. Sage, Ph.D., Ed.

22. About the same time Lucius Manlius and Gaius Helvius, when they had marched up as far as the slopes of the hill admitted of progress, after they had reached the impassable places changed their direction towards that part of the mountain which alone [2??] offered a road, and began to follow the consul's column, each at a moderate distance as if by agreement, being compelled by necessity itself to do what would from the first have been the best thing to do;¹ [3] [p. 77]for reserves have often, on such unfavourable terrains,² been of the greatest service, that when the leading troops have perhaps been thrown into disorder the reserves may both shield the defeated and, being themselves fresh, take up the fight. [4] When the leading standards of the legions came to the hills which had been captured by the light troops, the consul ordered the men to take breath and to rest for a little while; [5] at the same time he called their attention to the corpses of Gauls strewn over the hills and asked them what, when light-armed troops had worked such havoc in the fight, was to be expected of the legions, what of regular weapons, what of soldiers of the stoutest hearts? Their camp, he said, remained to be taken, into which the enemy had been driven in confusion by the light troops. [6] Nevertheless, he ordered the light-armed men to lead the advance, and they, while the column was halted, had spent the time by no means idly, in collecting the weapons over the hills, that the supply of missiles might suffice. [7] Now they were approaching the camp, and the Gauls, lest their fortifications should offer them too little shelter, had taken post under arms in front of the rampart. Then they were overwhelmed by missiles of every kind, and the more numerous and the more crowded together they were, the less did any weapon fall without effect, so that in an instant they were driven back within the rampart, leaving only strong guards at the actual gates of the fortifications. [8] A vast quantity of missile weapons was discharged at the throng which had been driven inside the camp, and the shouts mingled with the wails of women and children showed that many were wounded. Against the troops who had [p. 79]blocked the gates at which they were posted, the³ antesignani of the legions hurled their spears. [9] The men indeed were not injured by them, but their shields in many cases were pierced and fastened together,⁴ nor did they longer resist the attack of the Romans.