The Athenians won the battle of Marathon because of skilled leadership from Miltiades, the Athenian and Plataean hoplites, good terrain, and morale.
Miltiades was the commander during the Battle of Marathon. He had spent time in the Chersonese which gave him possible Persian tactics. Miltiades decided that because the Persian cavalry was so large in numbers the Athenians would spread out and make the center the weakest part with the wings the strongest. As the center was the weakest part of the Athenian cavalry it wasn’t able to hold their own against the Persians. However, once the Persians were about to break through the center the wings closed in around the Persians trapping them and the Persians lost.
The Athenian and Plataean hoplites were at an advantage from the beginning in man-to-man fighting, as the hoplites were better armed than the Persians. The Athenians wore greaves that protected their legs and wore cuirass which protected their upper bodies and carried a shield. The Persians wore little armor and carried wicker shields.
The terrain at Marathon neutralised the strongest part of Persian forces, the cavalry. With the cavalry neutralised the Athenians had a better chance of winning. Miltiades tactic was to rush at the Persian center. By doing this it prevented the Persians from taking advantage of their superior numbers.
The Athenians and Plataeans were fighting for their homeland. Their defeat meant being enslaved or worse. This gave them more morale to fight. The Persian force was multi-national. Their victory at Marathon meant another country could be defeated and they could gain more power to their already powerful empire. This made the Persians less motivated than the Athenians.
The Battle at Marathon was a significant Battle as it demonstrated that the Athenians could defeat a powerful enemy without Spartan help. This was a turning point the Athens.
Overall, the Greeks were victorious