The Persians outnumbered the Greeks and the Greeks desperately needed help from Sparta's military base. Sparta was a warrior society in ancient Greece.
The Marathon War pt. 2
The Athenians sent one of their best runners, Phidippides, to go ask the Sparta base for help. The 140 mile course was mountainous and rugged. Phidippides ran the course in about 36 hours. Without any help from the Sparta army, Phidippides ran back to Athens (more 140 miles!)
End of War
3 hours (26 miles)
Without any help from the Sparta army, Phidippides ran back to Athens (more 140 miles!) Immediately, the Athenian army (including Phidippides) marched to the plains Marathon and prepared for battle.
The Athenian army was outnumbered 4 to 1 at the beginning, however, in the end, 6400 Persians bodies lay on the field while only 192 Athenian had been killed. The surviving Persians fled to sea and headed south to Athens where they hoped to attack the city.
Phidippides was called upon to run to Athens (26 miles away) to carry the news of the victory and the warning about the approaching Persian ships. He reached Athens in about 3 hours, delivered his message and then died shortly thereafter due to exhaustion. Sparta and the other Greek polies eventually came to the aid of Athens and were able to turn back the Persian attempt to conquer Greece.