The Persians embarked their cavalry to go around to Athens andcapture it in the absence of the Athenian army at Marathon. TheAthenians saw this and ran down and defeat the inferior Persianinfantry no longer protected by it cavalry.After winning that battle, the Athenians realised where thecavalry was headed and all 18,000 ran back to Athens to form upjust as the Persians were disembarking. The Persians, disappointed,sailed home.This run by the 18,000 was the origin of today's marathon runs,though today's pampered athletes don't have to carry weapons,shields and armour and run in sandals.