The Makedonian phalanx -- why such depth?

[PMBardunias]

...this argument has been put before, and dealt with before. The formation was NOT a special one devised for the occasion, and Xenophon is at pains to tell us so - he says it was the 'customary' formation or something stronger if Giannis is correct ( more like 'Rule' or 'Law' ) and I would agree with you that it was a simulated charge of the Phalanx.

Right, it simulated "a" phalanx, not "the" phalanx. There was no single option for the depth of a phalanx. here Xenophon has chosen the shallowest. With the same troops he could have chosen a depth of 8 or 16 depending on the troops they faced. Surely there is no logical problem with Xenophon being able to tell his men not to double down all the way to 4, but to form the 8 rank formation in close order? In another situation he could tell his men to move directly into close order during the 16 rank step. He also could line up whole lochoi along side each other with gaps between them as he might prior to deployment and then not deploy them at all and face the enemy in orthoi lochoi.

A moment's thought will demonstrate that the Greeks had no opportunity to devise or practise a 'special' formation for the occasion.....there is absolutely no evidence to suggest Hoplites, or Alexander's Sarissaphoroi for that matter, generally formed up more thinly at half the usual depth against 'Asiatics'.Your supposition flys in the face of the evidence ( little though it is)

Marathon comes to mind. It would be hard to find a better "test" of depth than marathon where the thinned center is broken through and the deep flanks are victorious.

Agreed....but again I have already referred to the fact that modern re-enactors, and Police facing rioters, have discovered that a line as thin as three deep cannot be burst through, no matter how deep the 'mob' charging them ....so four deep would seem to be adequate, allowing 3 deep to participate, and a fourth line of 'replacement' of casualties....a quarter of the force be it noted.

Not true. 3 deep can resist a "rush" by a small group of men, like a wedge for example, but a crowd can push through a rank of three men. What you are confusing with pushing is "herding", where police beat a crowd into moving away from them.

Excessive depth is a handicap, as Xenophon pointed out ( Cyropaedia)

I agree with Xenophon's obvious dig at Theban tactics- 100 ranks are too deep. If you read further though, you will see that he admits the enemy will break through his thin line unless the missiles of he rear rankers and the flank attacks of his other troops break them. It runs counter to your arguement that as the 5th/4th centuries progress we see phalanxes becoming generally deeper while concurrently the threat of envelopment is rapidly increasing due to better handling of light troops and cavalry.

The Macedonians 8 deep might be considered excessive...save that 5 deep could participate, leaving a similar proportion, this time 3/8ths, as reserves/supports. A formation 16 deep in close order, with 11/16ths not participating, is no longer 'linear'.....

You define participate as directly attacking. Participation can be simply adding to morale by standing behind the men who are fighting. Participation can also of cource being there to phisically block their rearward movement- of their own volition or by being driven back by the enemy. The sheer volume of formations deeper than 4 in the history of warfare speak to this benefit.

then there are the other factors such as the 'half-file' leaders etc of Xenophon and the manuals,

The ability to do something does not neccesitate its performance. Surely it would be a good idea to have the flexibility to double down thinner than normal should the need arise- as when scaring Cilician women.

and the impracticalities of trying to advance cross-country in a line a thousand yards long in close order ( can't be done!)

It would be odd if a greek with a shield and spear could not march across a field in close order while just about any early modern fellow with a shouldered musket seems to have been able to advance much farther shoulder to shoulder in much thinner lines.

And before Theban formations are again brought up, let me say we are here generalising on the typical, speaking of which, recollect that the 50 deep Thebans did not break through the Spartan line at Leuctra, where the Spartans, in their much thinner line, held on until their King was mortally wounded and those around him mostly casualties, only then giving way.

Precisely as I would predict with a crowd-like othismos. Coordinating the motions of 50 men ranks is very difficult, so the effective pushing power of the 50 ranks was not superior to the pushing power of the Spartan 12 ranks. What was superior is the stamina of the Thebans because the sheer mass behind the front lines made pushing them backwards increasingly difficult as with each step you pack them tighter and recieve more resistance. For the Spartans it was like pushing up hill.

If Spartan 'super troops' are argued, consider that Spartans in a deep column could not break through Arcadians in a normal 'close order' line (Xen 'History of my times' VII.4.23)

Same phenomenon as above.

Incidents like this show that too much depth was not in itself useful, and the dangers of being outflanked. ( the Thebans at Leuctra were only saved from this by Pelopidas' famous charge)....Xenophon was right about depth!

And yet, the deep formation worked at delium, leuktra and mantinaea. It was vulnerable to outflanking, which is why once the novelty wore off it was discarded as a tactic, but it was ideal at breaking through ranks of men. In general I balk at claiming Pagondas and Epaminondas were tactic morons hock:

As for the photo, it is no more a realistic reproduction of battle than a Rugby scrum or Gridiron scrimmage.....

and no less.