Titus Livius (Livy), The History of Rome, Book 28
Cyrus Evans, Ed.

2. He was now about three thousand paces from the enemy, when as yet none of them had perceived him. The ground was covered with craggy places, and hills overgrown with bushes. [2] Here in a hollow valley, and on that account unexposed to the view, he ordered his men to sit down and take refreshment. [3] In the mean time the scouts returned, confirming the statements of the deserters. Then the Romans, collecting their baggage in the centre, took arms, and marched to battle in regular array. They were a thousand paces off when they were descried by the enemy, when suddenly all began to be in a state of hurry and confusion. At the first shout and tumult, Mago quitted the camp and rode up at full speed. [4] As there were in the Celtiberian army four thousand targeteers and two hundred horsemen, this regular legion, as it formed the flower of his troops, he stationed in the first line; the rest, composed of light-armed, he posted in reserve. [5] While he was leading them out of the camp thus marshalled, the Romans discharged their javelins at them before they had scarcely cleared the rampart. [6] The Spaniards stooped down to avoid the javelins thrown at them by the enemy, and then rose up to discharge their own in turn; which the Romans [p. 1163]having received according to their custom in close array, with their shields firmly united, they then engaged foot to foot, and began to fight with their swords. [7] But the ruggedness of the ground, while it rendered ineffectual the agility of the Celtiberians, who were accustomed to a skirmishing kind of battle, was at the same time not unfavourable to the Romans, who were accustomed to a steady kind of [8??] fight, except that the narrow passes and the bushes, which grew here and there, broke their ranks, and they were compelled to engage one against one, and two against two, as if matched together. [9] The same circumstance which obstructed the enemy's flight, delivered them up, as it were, bound for slaughter. [10] And now when almost all the targeteers had been slain, the light-armed and the Carthaginians, who had come up to their assistance from the other camp, having been thrown into confusion, were put to the sword. [11] Not more than two thousand of the infantry, and all the cavalry, fled from the field with Mago before the battle was well begun. The other general, Hanno, was taken alive, together with those who came up when the battle was now decided. [12] Almost the whole of the cavalry and the veteran infantry, following Mago in his flight, came to Hasdrubal on the tenth day in the province of Gades. The newly-raised Celtiberian troops, stealing off to the neighbouring woods, fled thence to their homes. [13] By this very seasonable victory, a stop was put to a war which was not by any means so considerable as that to which it would have grown, had the enemy been allowed, after having prevailed upon the Celtiberians to join them, to solicit other nations also to take up arms. [14] Scipio, therefore, having liberally bestowed the highest commendations on Silanus, and entertaining a hope that he might bring the war to a termination, if he did not impede it by a want of activity on his own part, proceeded into the remotest part of Spain against Hasdrubal. [15] The Carthaginian, who then happened to be encamped in Baetica, in order to prevent his allies from wavering in their allegiance, retired quite to the ocean and Gades, in a manner much more resembling a flight than a march. [16] He was afraid, however, that while he kept his forces together, he should form the principal object of attack. Before he crossed the strait to Gades he sent them into different cities, that they might both [p. 1164]provide for their own safety by the help of walls, and for that of the town by their arms.