Titus Livius (Livy), The History of Rome, Book 30
Frank Gardener Moore, Professor Emeritus in Columbia University, Ed.

11. About the same time, as it happened, after [p. 403]Laelius and Masinissa had reached Numidia in about¹ fifteen days, the Maesulians, that is, the kingdom of Masinissa's father, joyfully submitted to his rule, as that of a long-wished-for king. [2] Syphax, when his commanders and garrisons had been driven out, confined himself to his old kingdom with no intention of remaining inactive. [3] Love-sick, he was spurred on by his wife and father-in-law, and he had men and horses in such abundance that, when the forces of a kingdom that had flourished for many years were before his eyes, they could have roused a spirit that was even less barbarous and uncontrollable. [4] Therefore, concentrating all the men fit for war, he assigned them horses, arms and missile weapons. He organized cavalry in troops, infantry in cohorts, in the manner he had formerly² learned from Roman centurions. With an army no smaller than that which he had had before, but almost entirely raw and untrained, he at once advanced against the enemy. [5] And after a camp had been pitched not far away, at first a few horsemen rode forth from the outposts, scouting from a safe distance; then being driven away by lances they dashed back- to their own men. [6] Next in order came attacks made from both sides and, as men beaten back were inflamed by anger, more and more came to help them —the [7] usual provocation in cavalry engagements, when either hope adds reinforcements to the successful or anger to those who have been repulsed.

[8] So on this occasion, the battle having been begun by a few, all the cavalry of both sides in the end were sent pouring out by their zest for the fray. And so long as it was purely a cavalry battle, the great [p. 405]numbers of the Masaesulians,³ while Syphax was⁴ sending out huge columns, could hardly be withstood. [9] Then when Roman infantry⁵ by a sudden movement into the openings made for them by troops of their own cavalry had steadied the battle-line and checked the wild charge of the enemy, the barbarians at first gave their horses less rein, then were at a standstill and all but confounded by the strange tactics. [10] Finally they not only gave way before the infantry but did not withstand the cavalry either, who were emboldened by the protection of infantry. [11] And now the units of legionaries⁶ also were approaching. Then indeed the Masaesulians failed to sustain not only the first attack but even the sight of the standards and arms. Such was the effect either of remembering former defeats or of their present alarm.