The Makedonian phalanx -- why such depth?

[Paullus Scipio]

Mythos Ruler wrote:

Then what exactly did he learn and apply if the Macedonian phalanx fought in a depth of 8 men, a similar depth to the old-school phalanx employed by the city-states? I mean, wasn't the chief innovation of the Thebans a deeper phalanx used to smash the typical 8 or 12-deep formation or am I missing something?

I think you may have missed something I wrote in an earlier post by me......

Similarly, an 'average' depth for a Hoplite spear armed phalanx was 8 deep ( though 12 and 16 and even deeper by the Thebans are known, the latter when using 'column' against line) and this too is in 'open' order, so that when 'closed up' into 'pyknosis' the line is just 4 deep, with each man on a 3 foot frontage, as Xenophon famously tells us. The front 3 ranks of Hoplites could use their spears, with a rear rank of 'file closers', again not wasting the 'fighting strength' of the formation.....

....so the Macedonian Phalanx depth is still double/deeper than that of a typical Hoplite phalanx.....the Hoplites in close order are typically 4 deep to the Macedonian 8.

Note also that the Theban 'deep' phalanx is usually only part of their overall line - tactically it forms a 'column' whose depth/weight is used against part of a phalanx line to burst through.... classic 'Column versus Line'.