The Makedonian phalanx -- why such depth?

[Paralus]

Well, the manuals certainly represent the epitome of the full evolution of Greek/Hellenistic drill. As to what the Macedonian style phalanx, especially the later ones, could and couldn't cope with depended on too many factors, not just it's drill standards. However, at Sellasia, the Macedonian phalanx ascended mountains, before, on their right tackling a Spartan fortified camp, and on their left ascending a mountain, marching over the crest and tackling the Spartan phalanx in a fairly narrow curved saddle....all of which gives the lie to the 'flat ground only' idea, or that the later Macedonian phalanx was necessarily worse than it's Alexandrian forebears. These are demonstrably incorrect cliches. Polybius' remarks are generalisations, and should be recognised as such....though I would agree that clearly what he says is generally true.

Polybios’ remarks on the phalanx are framed by, indeed relate to, the just described battle of Cynoscephalae. It matters little that he precedes them by stating that “as promised here is my description” to paraphrase. The battle just described is the palate for painting the manifest drawbacks – as Polybios sees them – of the formation. The fact is that Philip’s (V) phalanx was not that of Sellasia and it most certainly was not that of Issos or Gaugamela; nor were the peltasts the hypaspists of those battles or Hydaspes. As Livy claims (33.3):

After his envoys had returned from their fruitless mission to Rome, Philip decided to raise troops in every town in his kingdom. Owing to the perpetual wars which had for so many generations drained the manhood of Macedonia there was a serious lack of men of military age, and under Philip's own rule vast numbers had perished in the naval battles against the Rhodians and Attalus and in the campaigns against the Romans. Under these circumstances he even enrolled youths of sixteen and recalled to the colours men who had served their time, provided they had any stamina left.

Polybios is, correctly one thinks, describing a phalanx nowhere near the peak of its prowess. That he then ascribes the ‘qualities’ of this phalanx (and the latter at Pydna) to that of Philip II and Alexander III (in his tirade against Kallisthenes) is a result of the fact that he knows only what he currently sees. Therefore Alexander’s phalanx could not possibly have marched across such a ‘plain’ as at Issos (it demonstrably did); it could not possibly have dealt with a river (it did both at Issos and Granicus) and it most certainly could not deal with being breached (it did both at Issos and Gaugamela.

More importantly its commander in those actions seemed to have little doubt that it would.