The Athenians set up camp on the southern edge of the plain of Marathon and from the Sanctuary of Heracles, a position on nearby Mount Agriliki, they could keep a watchful eye on the road to Athens. The approach to this position was narrow, preventing a flanking maneuver by the Persian cavalry and keeping their forces stuck on the edge of the plain.

As the Athenians waited, a thousand additional men arrived from the town of Plataea, a closely allied town. Ionian Greek conscripts, drafted into the Persian army, are believed to have further aided the Athenian cause by passing on information about the Persian cavalry which, after a four day standoff, set off on a separate expedition to reach Athens by sea.

Soon after dawn the next day the Athenians advanced 'at the double', running in their heavy hoplite armor against Persian bowmen, whose arrows became increasingly effective within the last two hundred meters. Once the gap was narrowed, however, the superior skills and armor of the Greeks quickly became apparent...