The Makedonian phalanx -- why such depth?

[Paralus]

"Battle Order" = the dispositions of the units in the phalanx, which unit stood alongside which on the battlefield e.g. at Cyrus' review, we have the "battle order" of Menon and his troops on the right,Clearchus on the left and the other Greek generals in the centre......

"Battle formation" = the formation a particular unit or phalanx stands in, thus the aforesaid mercenary units stand in close order 4 deep......( but could also be other formations e.g. 8 deep in open/normal order......

However, confusion is understandable since some authors/translators use the terms interchangeably :x :roll:

Glad you cleared that up. In which case when you state that Xenophon's mercenaries formed up in "battle formation" they have formed in close order. To quote Xenophon (1.2.15):

...form their lines and take their positions just as they were accustomed to do for battle, each general marshalling his own men. So they formed the line four deep..

The Greek is: ekeleuse de tous Hellênas hôs nomos autois eis machên

Arrian, via Ptolemy (and likely Callisthenes), describes Alexander's movements at Issos in the same terminology (2.8.3, 8):

...but when they advanced into the open country, he began to draw up his army in battle order (eis machen)...

...Alexander's approach for battle (prosagon ede Alexandros os es machen)...