How did Greece win the Persian Wars?

Answer 1

By first concentrating on the Persian fleet, and when they had destroyed it, were able to concentrate the Greek city contingents and defeat the Persian army and its Greek allies with its superior armoured infantry.

Answer 2

First by cripplng the Persian fleet at Salamis, which removed the amphibious threat to the southern Greek cities, and allowed them to stop keeping their forces at home to defend their cities, and they could now concentrate them at Platia the following spring.

Secondly, the Persian supply fleet could no bring food by sea, and the Persian King had to take half his army home as a poor country such as Greece could not support them all through the winter.

The opposing forces were now fairly even, and by fighting in broken country at Plataia the superior Persian cavalry was neutralised. The superior Greek armoured infantry were able to break the lightly armoured Persian infantry unprotected by their cavalry.