The Makedonian phalanx -- why such depth?

[Paullus Scipio]

Paul B. wrote:

I don't think we can state that doubling by interposing half files is the way they formed close order. Aelian makes clear that there are various ways of "doubling" in the same space and of extending and contracting the line. The one he describes in the most detail is the moving of alternate men in a file forward and to the side, like shuffling cards- second man in a file becomes the first in a new one.

...I did not mean to imply it was the only possible way, though it is the only way we know of for the earlier Hoplite period. It should be remembered that Aelian/Asclepiodotus/Arrian or rather their common source was writing of the Hellenistic phalanx in it's final and most sophisticated form, and the most complex drills devised....

He also describes the wholesale lateral movement of troops to close up or space out. This appears to have been done at Cynocephale for example: "he ordered the peltasts and heavy armed to double their depth and close up to the right." One of the tacticians described this as halving their frontage and doubling their depth, thus the man on the left end of the line had to hustle right over a long distance! We could argue whether they ended up in close or opened order, but the point is that men were expected to make such gross lateral movements on the field of battle.

Cynoscephalae, in 197 BC against the Romans is one of the last battles of the Hellenistic Phalanx, and significantly is the only battle ( that I can recall off the top of my head), where such lateral movement is described, and in this instance it is for a very specific reason, namely that the Right half of the Phalanx occupied a ridge line ( the Ground of Tactical Importance) until the Left half of the Phalanx came up, then closed up laterally to make room for the left half.....
This highly risky manouevre was carried out with the Romans a considerable distance away, somewhere at the foot of the ridge, and with a peltast screen in place to cover it. It can be regarded as the 'exception which proves the rule', and the marching up of half-files to form close order was the most common/typical way of closing up for action, precisely because it did not involve a change of frontage....

The reference to the thinly disguised 'Spartans' getting to 6 ranks deep in close order in Xenophons Cyropaedia is another piece of evidence for my hypothesis, by the way - Spartans are commonly described as "12 deep" which again would refer to normal/open order, before they closed up to 6 ranks deep for the clash of battle.....