"At six in the morning, the Athenians began their charge. A hail of arrows from the Persian archers rained down on them..."
For several days neither side moved. The Athenians had no choice but to hold their position; without cavalry and hopelessly outnumbered, how could they do battle at Marathon? If enough time went by, perhaps the Spartans would arrive as reinforcements. But what were the Persians waiting for?
Before dawn on August 12, some Greek scouts ostensibly working for the Persians slipped across to the Athenian side and reported startling news: under cover of darkness, the Persians had just sailed for the Bay of Phaleron outside Athens, taking most of their cavalry with them and leaving a holding force of some 15,000 soldiers in the plains of Marathon. They would take Athens from the sea, then march north, squeezing the Athenian army at Marathon between two larger forces.
At six in the morning, the Athenians began their charge. A hail of arrows from the Persian archers rained down on them, but they closed in on the enemy so quickly that the battle now had to be fought hand-to-hand and, as Miltiades had foreseen, in close combat the Athenians were superior. They pushed the Persians back into the marshes at the north end of the plain, where thousands drowned. The waters reddened with blood. By nine in the morning, the Athenians had control of the plains, having lost fewer than two hundred men.
Although emotionally spent by this battle, the Athenians now had only around seven hours to make the twenty-four miles from Marathon back to Athens in time to stop the Persians. There was simply no time to rest; they ran, as fast their feet could take them, loaded down in their heavy armor, impelled by the thought of the imminent dangers facing their families and fellow citizens. By four in the afternoon, the fastest among them had straggled to a point overlooking the Bay of Phaleron. The rest soon followed. Within a matter of minutes after their arrival, the Persian fleet sailed into the bay to see a most unwelcome sight: thousands of Athenian soldiers, caked in dust and blood, standing shoulder to shoulder to fight the landing. The Persians rode at anchor for a few hours, then headed out to sea, returning home. Athens was saved.
-The 33 Strategies of War, by Robert Greene
Underestimating the Athenians, the Persian army divided their forces and sent their ships to Athens. Here they would take the city and close in behind the Athenian army. Surrounded the Greeks would have no chance. Instead, the 10,000 Athenians defeated 15,000 Persians in only 3 hours and ran 24 miles from Marathon to Athens arriving just as the first ship came into sight. The Persians were shocked and decided to go home. This is how 10,000 Greeks defeated an 80,000 man Persian army and the tradition of running Marathons inspired.
The tradition of marathons was inspired by the legend of an ancient Greek messenger who raced from the site of Marathon to Athens, a distance of nearly 25 miles. He carried with him news of the Greek victory over an invading army of Persians. After making his announcement, the exhausted messenger collapsed and died.