Ten years earlier in 490 B.C. The Persian King Darius tried to do the same thing except he landed at Marathon which is not far from Athens.
Herodotus put the Persian number at 100,000 but modern historians think it was closer to 25-35,000. The Athenians numbered around 10,000 (plus a thousand Plataens).
Darius army was a professional one trained and equipped by the Persian Empire. The Greeks were free men and the soldiers who could afford to wore heavy armor (hoplites). The ones who could not afford the armor were something like slingers and archers.
The Greeks gave Darius a bloody nose at Marathon but that was not the end. The Athenians who must have been exhausted from the battle, nevertheless marched the 26 miles to Athens and when Darius ships arrived at the port of Piraeus he found the heavily armed Greeks waiting for him.