Ancient army numbers

[Robert Vermaat]

Macedon does however explain quite clearly how it would be feasible for the army to have been quite large, and the Persians capable of raising it and supplying it.

Indeed he does! But to me that's also where it ends - in pure theory.
Of course it could be possible, humanly speaking, if you had the time, the power, the means.
But that is my point in all this (and of Roach also, I suspect) is the lack of hard evidence. I mean, no-one takes Herodotus literally here, but if we follow this through, what do we have?

Preparation:
An operation of this size must have taken years to prepare. The logistics of it all must have been staggering. I mean, look at what was done before Normandy 1944! And that with only a tribal-based feudalist iron Age society, the pace with which such plans could have been implemented must have been a good deal slower than what the Allies needed – and that was months and months.

Next, where do you put all those men? And how do you control all of them?
Suppose the larger part of the army would assemble in one or two spots, perhaps more, and march in separate columns towards Europe (I keep thinking of Napoleon’s and Hitler’s invasions of Russia) to keep a grip on them. But even in 3 or 4 groups, the strain on the countryside (friendly countryside) must have been enormous.
So do we have any indication where this could have taken place? Camps for hundreds of thousands of men?

The same goes for the fleets, which would have been essential for transport and supplies while the army was in Greece – I think everybody will agree with me that supply lines over land would have been to long and would have needed too much transport to even contemplate them as feasible.
Where would these fleets assemble? Or would we have to think of a great number of smaller fleets, each commanded separately?

For both land and sea forces, the same problem would occur: how do you control them? Persia was a feudalist state, I doubt very much that they would have been able to control each army and fleet from a central point, and I just do not see how an operation like this could have relied on commanders operating independently.

Infrastructure

So I suppose that this was prepared in advance, by setting up storage facilities for food, water (especially water!), complete with live animals and their fodder.
Where are these facilities? There must have been dozens and dozens, each very large, for all the grain, non-perishable food, water, fodder and containment pens for the large herds of animals.

This is where many later armies failed. They could not get the supplies to the troops, even when organized far better than Xerxes. So how could he have managed where they all failed?

Is there any evidence for storage facilities where the fleets could have picked up their loads? I mean, this was so huge (and see my point on command) that it’s almost impossible to expect each city, island and region to act independently as a supply base.

Invasion

Next stop: Greece. Where did they put their supplies when in enemy territory? Even when we suppose that the ships dropped anchor on the coast and left their supplies there, what? How long was the column of this army, how were supplies distributed over so many men? How did the ships know where to head, as it would be impossible to communicate the advance of the troops to the fleets, apart from with a delay of days at best and probably weeks? The troops would have to starve or take all from the enemy.
Or, there would have been pre-arranged harbors that were set up after they were reached by the army? Same problem, but at least there would have been supplies coming in.
Essentially, the army would have been able to gather enough supplies from the enemy, in case the fleets did not come through (storms, enemy action, logistical mistakes being quite to be expected).
But then, if supplies by sea would have been so very difficult to organize, command and control, could Xerxes have even relied on that?

Concluding, it’s these practical problems that to me make this theory impossible to put into practice.