In the Eighteenth book of his Histories Polybius wrote,
“As for King Pyrrhus of Epirus, he employed not only Italian weapons but also Italian troops and alternated maniples and units of the phalanx in drawing up his battle order against the Romans. But even with the help of these methods he did not succeed in winning a victory, and the outcome of all his battles was somewhat indecisive.” (Polybius XVIII.28).
This extract is part of Polybius' famous comparison of the Macedonian and Roman military systems in which he explains why the Romans triumphed in the wars between the two nations. His argument essentially is that Pyrrhus, a skilled commander, recognised the weakness of the Macedonian system and sought to adopt Italian tactics. But is Polybius right?
The first thing we notice is that Polybius, or possibly his source, was wrong when he says the battles Pyrrhus fought were indecisive. Pyrrhus routed the Romans at Heraclea (280 BC) and was victorious a year later at Asculum (279 BC). So why would Pyrrhus adopt Italian troops and tactics when he was winning and defeating Roman armies?
We can be certain Pyrrhus did not employ Italian troops at Heraclea. He had only recently arrived in Italy and Plutarch tells us he felt great pride at winning that battle using only the forces he had brought with him. He did have some troops from Tarentum (who fought in a traditional phalanx formation) with him but it is unlikely they saw any significant involvement in the battle. At Asculum he fought the Romans with various allies from Southern Italy. Plutarch describes the phalanx fighting as normal, and fighting well. But Plutarch is not our only source for Asculum.
Dionysius of Halicarnassus lists Pyrrhus' order of battle (as it relates to the infantry, cavalry deployment has been omitted to save space),
“...the Macedonian phalanx the first place on the right wing and placed next to it the Italiot mercenaries from Tarentum; then the troops from Ambracia and after them the phalanx of Tarentines equipped with white shields, forced by the allied force of Bruttians and Lucanians; in the middle of the battle-line he stationed the Thesprotians and Chaonians; next to them the mercenaries of the Aetolians, Acarnanians and Athamanians, and finally the Samnites, who constituted the left wing.” (Dionysius of Halicarnassus XX.1-3)
Here we see the tactical deployment to which Polybius referred. Yet what is interesting is that Pyrrhus has not broken up 'his' Macedonian phalanx, far from it, instead he has placed them as one group in the position of honour on the right. Asculum was a bigger battle than Heraclea and, although we can discount fanciful estimations of 70,000 on each side, Pyrrhus lacked the manpower to present an unbroken front of Macedonian phalangites. He was therefore forced to adapt his tactics and rely on his allies who constituted a considerable section of his army. In the actual fighting the Macedonian phalanx performed admirably, defeating both Roman and Latin Legions opposed to it. Meanwhile it was his Italian troops who performed badly and nearly cost him the battle, fleeing from the field.
Considering how effective the Macedonian Phalanx was at both Heraclea and Asculum we can ignore any suggestion that they were in some way inferior to the Roman troops of the time. Indeed the professional, Macedonian trained infantry Pyrrhus brought with him to Italy were probably the finest quality troops available at the time. The problem Pyrrhus had was that he did not have enough of them.
Further the use of mercenaries, or other infantry, to separate units of the phalanx was not unheard of. This was done to make the line of battle more flexible, not because Pyrrhus saw the Italian maniple as being superior to the Macedonian. Polybius, or his source, clearly failed to understand Pyrrhus' tactics at Asculum and then misrepresented them.
We must always be cautious when dealing with ancient sources. We must recognise that writers, even ones as good as Polybius, made mistakes, omissions and could often openly favour one side. That Polybius favoured the Romans and the Scipio family is beyond dispute. When writing about Pyrrhus' tactics Polybius is probably guilty only of ignorance and misinterpretation. His work in general seems to show that he was unaware of how the Macedonian phalanx had evolved over the years and that it was not always like the Second century BC model of which he was familiar.
Translated versions of Polybius, Plutarch and Dionysius are all available on-line.