Setting the Stage
The first two decades of the fifth century B.C. marked one of the great turning points in world history. These were the years of the Persian and Greek wars. The powerful Persian Empire in 546 B.C. extended from Asia to Eygpt to what is now Turkey. This great empire built the first Suez Canal which linked the Mediterranean Sea with the Red Sea.
Greece on the other hand, consisted of a scattering of independent city-states, called poleis. These early city-states spawned the democratic ideas that have persisted into modern times. Athens eventually became the largest and most prosperous polis. Another Greek polis, Sparta, was not so democratic. They kept their kings and maintained a conservative, regimented society built around military training and the art of war.
The Persian/Greek War
The Persian Empire over the years expanded to the Mediterrean Sea. In the process some Greek settlements were conquered. Ionia was one such settlement. After many years, they tried to revolt against the Persians but the uprising was immediately squashed by the powerful Persian Army. By the year 490 B.C., the Persian Army was ready to expand their territory and move into Europe. They landed a large force just outside of Athens on the plains of Marathon and prepared for attack.
The Role of Phidippides
The Athens, vastly outnumbered, desperately needed the help of Sparta's military base to help fend off the attack. Time was short, so the Athenian generals send Phidippides (or Philippides) a professional runner to Sparta to ask for help. The 140 mile course was very mountainous and rugged. Phidippides ran the course in about 36 hours. Sparta agreed to help but said they would not take the field until the moon was full due to religious laws. This would leave the Athenians alone to fight the Persian Army. Phidippides ran back to Athens (another 140 miles!) with the disappointing news. Immediately, the small Athenian Army (including Phidippedes) marched to the plains of Marathon to prepare for battle.
The Battle of Marathon
The Athenian Army was outnumbered 4 to 1 but they launched a suprise offensive thrust which at the time appeared suicidal. But by day's end, 6400 Persian bodies lay dead on the field while only 192 Athenians had been killed. The surviving Persians fled to sea and headed south to Athens where they hoped to attack the city before the Greek Army could re-assemble there.
Phidippides was again called upon to run to Athens (26 miles away) to carry the news of the victory and the warning about the approaching Persian ships. Despite his fatigue after his recent run to Sparta and back and having fought all morning in heavy armor, Phidippides rose to the challenge. Pushing himself past normal limits of human endurance, the reached Athens in perhaps 3 hours, deliverd his message and then died shortly thereafter from exhaustion.
Sparta and the other Greek polies eventually came to the aid of Athens and eventually they were able to turn back the Persian attempt to conquer Greece.
Concluding Remarks and Beginning of Olympic Marathon Races
The Greek victory marked one of the decisive events of world history because it kept an Eastern power (the persians) from conquering what is now Europe. The victory gave the Greeks incredible confidence in themselves, their government and their culture.
In the two centuries that followed, the Greek culture spread across much of the known world. It made Europe possible and in affect won for civilization the opportunity to develop its own ecomomic life.
Modern European-based nations such as the United States and Canada can trace their growth straight back through an unbroken chain of Western historical events back to the Victory at Marathon.
Centuries later, the modern Olympic Games introduced a "marathon" race of (40,000 meters or 24.85 miles). The winner was Spiridon Louis, a Greek postal worker from village of Marusi and veteran of several long military marches , His time was 2 hours, 58 minutes, 50 seconds for the 40 kilometer distance (average pace of 7:11 minutes per mile).
At the 1908 Olympic Games in London, the marathon distance was changed to 26 miles to cover the ground from Windsor Castleto White City stadium, with 385 yards added on so the race could finish in front of King Edward VII's royal box. After 16 years of extremely heated discussion, this 26.2 mile distance was established at the 1924 Olympics in Paris as the official marathon distance.
Source: http://www.lakepowell.net/marathon.html