Note 62 — Chapter IV · PERSIAN OPERATIONS IN EUROPE: B.C. 493–490. MARATHON.
Reading edition
Various exaggerated estimates of these numbers are given in later historians. Modern authorities have formed estimates varying from 30,000 to 50,000.
6400 Persians fell at Marathon, when the Persian centre must have been almost wiped out, but when not more than half the Persian army was engaged in the battle. This would suggest 20,000 as the number of Persians at Marathon, and about 40,000 as the number of the whole expedition.