Ancient army numbers

[Robert Vermaat]

Hi George,

As I have often said, I am of those few who seem to sometimes be stubbornly reluctant to dismiss the accounts of the ancients with a light heart. I think that we seem to greatly underestimate their capabilities.

Well, some may do this with a light heart, I’m not one of them. On the other hand, numbers are to be treated with extreme caution when dealing with sources in general, as we have to with Ancient sources. The biblical number of Israel being able to field a million men-at-arms are no different than the million men invading Greece.

Regarding the invasion of Greece by Xerxes army, I have no doubt that this army was large, that much is clear from the sources. Whether we are to trust the estimates presented to us by the sources is quite another matter. Overestimating an army is quite a normal practice, and I generally mistrust round numbers such as ‘100.000’, but that’s me.

But even if we disregard the level of ancient source trustworthiness, we can ask questions about more practical matters.

Your first question rightly regards logistics. However, you don’t seem to question the amount of supplies. Why not? The Persian empire, though vast, was not a vast exporter of food. It controlled Egypt and Asia Minor of course, but we can hardly expect the local populations to have starved while their food was being transported to the Greek War effort.
But even leaving that question aside, did the Persian state indeed have the logistical capabilities to feed such a vast host? I’m no expert, but I have not yet come across any evidence that tells us that they did. I’d love to be proven wrong though.

Next question, army numbers. From your post I seem to understand that you consider the Greek forces to have been a certain number and from that that a vastly superior number of Persians was needed, making a very large force acceptable?
Where did this large Persian army come from? Even when we look at far better documented campaigns (Xenephon, Alexander) we never hear of armies even a fraction of the numbers (5 million!!) that you seem to find acceptable. Even the largest numbers given to the entire Roman army (Agathius, more than 600.000) is dwarfed by that number. I really don’t understand where you find such a number, apart from perhaps taking some percentage of an estimated total of the Persian population?
The same goes for the Greek forces for that mater: a 100.000 at Plataea as a fraction of the Greek forces – are there sources available that ever mention all Greek armies, added together, as 500.000? If they had been able to muster such forces, the Romans would never have managed to gain a foothold! Or had the Greek population shrunk that much by the time of the Roman invasion? Or are you counting every man, woman and child involved in keeping the warrior in the field? I believe the ratio is 5 to 1, so for every soldier you’d need 5 non-combatants? That would explain large armies but not large fighting forces.

Also, the matter of logistics is to be considered. Greek forces, being close to home and able to be supplied locally, would logically represent a much higher percentage of the population than an invasion force far away from home.
Considering the Persian fleet, I can understand how their crews would inflate the numbers of the army, but the crews would not have been soldiers but sailors from the Levant, a force than would always have a certain number – you can’t easily train ship’s crews within a short time. You have to work with what you already have: building warships is one thing, but training as many new crews is quite another. A number of 300.000 seems excessive. If they had numbers like these, they would have crushed the Greek navies due to vastly superior numbers alone.

Land produce to me is partly irrelevant for Xerxes' campaign before leaving Mardonius back. If the Persian state was able to feed xxx.xxx soldiers at home, it could feed them abroad as long as it could transport the supplies to them.

And is exactly the question. Back to the question asked before – where is that superior Persian organization that could feed armies twice the size of the entire Roman army at it’s highest estimate? Indeed, if the Persian empire ever counted as many as 50 million inhabitants it could probably feed them, and that they an administration worthy of their salt is also a given. But that’s not the same as fielding a million men and feeding them by sea and land. Napoleon tried to do that with a force of 600.000 in the early 19th century and failed miserably. I just don’t see that the Persians, essentially a tribal kingdom fresh out of the bronze Age, succeeded in a much, much more complex operation with a vastly larger force where the French, quite adapt at these operations, failed.