The Persian Empire wanted to take over Ionia but the Ionians revolted. The Greeks and the Ionians were not good allies but they sent troops to help fight the Persians.
This is the Greeks and the Persian empire fighting in the Battle of Marathon. This battle happen because of the Ionian Revolt. The Persians wanted to get back at the Greeks.
Pheidippides was a Greek soldier that ran from The Battle Of Marathon to Athens to tell them to not give up.
Thermopylae was a narrow cliff side where 300 Spartans and about 7,000 Greeks fought hundreds of thousands of Persian soldiers. They fought here cause the narrow area only allowed a certain amount of soldiers on each side to fight.
The Persians went into the passage that leaded them behind the Spartans. The Greeks retreated and the Spartans ended up getting surrounded and all died.
The Persians continued on to defeat the Greeks. But the Greeks surrounded the Persians. Since the Greek boats were small and the Persians were large the Greek boats could maneuver and ram the Persian Navy. The Persians were defeated.