Titus Livius (Livy), The History of Rome, Book 33
Evan T. Sage, Ph.D. Professor of Latin and Head of the Department of Classics in the University of Pittsburgh, Ed.

8. The news was more encouraging than their success in the battle warranted, since one after another, coming back from the field, shouted out that the Romans were fleeing in terror, and [2] this compelled Philip, though against his will, reluctant, and maintaining that it was a rash undertaking and that he liked neither the place nor the time, to commit his entire force to the action. [3] The Roman also did the same, from necessity rather than to seize an opportunity for fighting. The right wing, with the elephants alined in front of the standards, he held in reserve; [4] with the left and all the lightarmed troops he attacked the enemy, reminding them at the same time that they would meet the same Macedonians whom they had driven out and defeated in battle in the passes of Epirus, defended by mountains and rivers, conquering the difficulties of Nature herself, the same Macedonians whom they had previously defeated under the leadership of Publius Sulpicius, when they held the pass to Eordaea; [5] that the Macedonian kingdom rested on reputation and not on strength, and that even this reputation had at last wholly faded away. [6] By this time they had come up to their men stationed in the lowest part of the valley, who, encouraged by the arrival of the army and the general, renewed the [p. 297]battle, charged, and again drove back the enemy. [7] -¹ Philip with the peltasts and the right wing of the infantry, the strength of the Macedonian army, which they called the phalanx, advanced on the run to meet the enemy, ordering Nicanor, one of [8] his nobles, to follow at once with the rest of the army. [9] At first as he reached the ridge and saw that the battle was over there, with a few weapons and a few corpses of the enemy lying about, and that the Romans had been driven back from there and that the battle was raging near the enemy's camp, he was filled with excessive joy; [10] presently, as his men were retreating, made uncertain by the reversal of fear, he debated in terror whether he should withdraw his men to their own camp; [11] then, as the enemy came nearer, when his men were being cut down in flight and could not be rescued unless they were reinforced, and not even he had any safe line of retreat, he was compelled, though his whole force had not come up, to try desperate measures. [12] On the right flank he placed the cavalry and the light infantry who had been in the battle; [13] he ordered the peltasts and the Macedonian phalanx to put aside their spears, the length of which was a hindrance, and to engage with swords. [14] At the same time, to prevent the line from being easily broken through, he diminished the front by half and doubled the depth by extending the files backward, so that the formation was deep rather than wide; he also ordered the troops to lessen intervals, so that man stood close to man and arms to arms.²

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