Ancient army numbers

[Sean Manning]

I thought the small size of Consular armies was another thing that set them apart from many ancient forces, which relied a great deal on force of numbers?

The problem is that all the evidence we have for massive Gaulish and Persian armies is Greek and Roman sources on the other side. When we look at how they moved, or how long their battle lines were, or compare later armies raised in the same area, we tend to get figures in the tens not hundreds of thousands of soldiers. We see the same thing in medieval chroniclers; the winning side usually insists that they were terribly outnumbered. All ancient armies tried to get a large force into the field, but it seems to me that numbers weren't more important than half a dozen other factors.

All that Xenophon knew about Artaxerxes' army was camp rumour and the sight of it advancing through the dust (and he keeps using indirect speech “they say that ...” in his description of Cunaxa rather than reporting things in his own voice as author). He gave numbers, because counting Persian armies was traditional, but he doesn't give us any reason to believe them. (In contrast, he gives us a list of contingents for Cyrus' Greeks, and gives a source for his numbers; Cyrus held two arithmoi kai exetaseis, “musters and counts,” of the Greeks).