How big was the Persian army?

Answer 1

Historian Herodotos lists provincial contingents throughout the empire of over two millionavailable for callout in the provinces of the empire.

For expeditionary forces, only the best cavalry and infantry were selected.

The invasion of Greece in 480 BCE probably amounted to three corps each of 10,000 cavalry and 50,000 infantry - a total of 150,000 infantry and 30,000 cavalry.

The fleet was probably 600 warships comprised of contingents supplied from Phoenician, Asian-Greek cities and Egypt, each ship with 200 rowers and marines aboard, and a similar number of cargo vessels to supply food for fleet and army. There would also have been a substantial number of camp followers.

Answer 2

The levy of the Persian Empire from all the provinces is described by the historian Herodotos as 2.5 million. These ranged in capability from knifemen from Africa to the best infantry from Persia.

When an expeditionary force was required, the Persians picked the best troops for the task. For the invasion of Greece in 480 BCE they selected three corps each comprised of 5 myriads (10,000) infantry and one myriad of cavalry. This gave a fighting force of 180,000. This structure also fits in with the commanders who are named in the ancient accounts.

Other wild figures given, based on Herodotos' estimate of the whole levy of the empire can be safely ignored. The idea of trying to feed millions of men, most not capable of serious fighting, in such a poor country as Greece is untenable. The Persians had to face the formidable armoured warriors of the Greek cities and brought along only their best soldiers.

When the Persian navy was defeated and they could no longer protect their sea supply line, half the Persian army was sent back to Asia as it could not be supported through the winter, so the Persian army was reduced to 90,000 plus about 40,000 Greek allies from central Greece who had come over to the Persian side.