When the Persians went to conquer Ionia. The Ionian Greeks weren't about to give up without a fight, despite the Ionians valiant effort and the aid of Athens, they lost to the Persians.
Persians landed at Marathon with the intent to conquer Athens because of the aid Athens provided in the Ionian revolt. They were met with Greek Forces, who were vastly outnumbered by the Persian forces. Despite this, the Greeks rained victorius with their phalanxes.
After the Greek victory at Marathon, Pheidippides runs 26 miles to Athens to tell the people not to give up the city to the Persians, he died of exhaustion after he reached the city.
Battle of Salamis
The battlefield of the Battle of Thermopylae took place between a steep mountain and the ocean.
The Greeks were able to hold off the Persian forces for 3 days until a Greek trader told the Persians about a secret pass through the mountains. 300 Spartans sacrificed themselves so the rest could live.
When the large Persian battleships entered the narrow channel, the small Greeks ships blocked off the Persian ships so they couldn't turn around, and the Greeks attacked the large Persian ships.