The battle being begun, Aemilius came in and found that the foremost of the Macedonians had already fixed the ends of their spears into the shields of his Romans, so that it was impossible to come near them with their swords. When he saw this, and observed that the rest of the Macedonians took the targets that hung on their left shoulders, and brought them round before them, and all at once stooped their pikes against their enemies' shields, and considered the great strength of this wall of shields, and the formidable appearance of a front thus bristling with arms, he was seized with amazement and alarm; nothing he had ever seen before had been equal to it; and in aftertimes he frequently used to speak both of the sight and of his own sensations. These, however, he dissembled, and rode through his army without either breastplate or helmet, with a serene and cheerful countenance.
On the contrary, as Polybius relates, no sooner was the battle begun, but the Macedonian king basely withdrew to the city Pydna, under a pretence of sacrificing to Hercules; a god that is not wont to regard the faint offerings of cowards, or to fulfil unsanctioned vows.
For truly it can hardly be a thing that heaven would sanction, that he that never shoots should carry away the prize; he triumph that slinks from the battle; he that takes no pains meet with success, or the wicked man prosper. But to Aemilius's petitions the god listened; he prayed for victory with his sword in his hand, and fought while entreating divine assistance.
A certain Posidonius, who has at some length written a history of Perseus, and professes to have lived at the time, and to have been himself engaged in these events, denies that Perseus left the field either through fear or pretence of sacrificing, but that, the very day before the fight, he received a kick from a horse on his thigh; that though very much disabled, and dissuaded by all his friends, he commanded one of his riding-horses to be brought, and entered the field unarmed; that amongst an infinite number of darts that flew about on all sides, one of iron lighted on him, and though not with the point, yet by a glance struck him with such force on his left side that it tore his clothes and so bruised his flesh that the mark remained a long time after. This is what Posidonius says in defence of Perseus.
The Romans not being able to make a breach in the phalanx, one Salius, a commander of the Pelignians, snatched the ensign of his company and threw it amongst the enemies; on seeing which, the Pelignians (as amongst the Italians it is always thought the greatest breach of honour to abandon a standard) rushed with great violence towards the place, where the conflict grew very fierce and the slaughter terrible on both sides. For these endeavoured to cut the spears asunder with their swords, or to beat them back with their shields, or put them by with their hands; and, on the other side, the Macedonians held their long sarissas in both hands, and pierced those that came in their way quite through their armour, no shield or corslet being able to resist the force of that weapon. The Pelignians and Marrucinians were thrown headlong to the ground, having without consideration, with mere animal fury, rushed upon a certain death. Their first ranks being slain, those that were behind were forced to give back; it cannot be said they fled, but they retreated towards Mount Olocrus. When, Aemilius saw this, Posidonius relates, he rent his clothes, some of his men being ready to fly, and the rest not willing to engage with a phalanx into which they could not hope to make any entrance- a sort of palisade, as it were, impregnable and unapproachable, with its close array of long spears everywhere meeting the assailant. Nevertheless, the unequalness of the ground would not permit a widely extended front to be so exactly drawn up as to have their shields everywhere joined; and Aemilius perceived that there were a great many interstices and breaches in the Macedonian phalanx, as it usually happens in all great armies, according to the different efforts of the combatants, who in one part press forward with eagerness, and in another are forced to fall back. Taking, therefore, this occasion, with all speed he broke up his men into their cohorts, and gave them order to fall into the intervals and openings of the enemy's body, and not to make one general attack upon them all, but to engage, as they were divided, in several partial battles. These commands Aemilius gave to his captains, and they to their soldiers; and no sooner had they entered the spaces and separated their enemies, but they charged them, some on their sides where they were naked and exposed, and others, making a circuit, behind; and thus destroyed the force of the phalanx, which consists in common action and close union. And now, come to fight man to man, or in small parties, the Macedonians smote in vain upon firm and long shields with their little swords, whilst their slight bucklers were not able to sustain the weight and force of the Roman swords, which pierced through all their armour to their bodies; they turned, in fine, and fled.
