Greeks had settled in Ionia and the Persians decided to take over. Athenian Greeks decided to send troops to help the Ionians.
Battle At Marathon
The Persians were mad that the Athenians came to help the Ionians fight them. So they came for revenge.
Soldier than ran to Athens around 26 miles away. He ran all the way to Athens to tell the Greeks that they were victorious and to not to give up without a fight. He then collapsed and died.
7,000 Greeks and 300 Spartans went to battle the Persians before they could reach Athens. They fought on a narrow ledge so that only a certain amount of Persians and Spartans/Greeks could fight at once.
A Greek traitor told the Persians about a small path that would lead them around them around the Greeks and Spartans. Greeks retreated but the 300 Spartans stayed to hold Persians off
The Persian army obviously was victorious at Thermopylae. They were still on the move but now it was the Navy. The Greeks were in a narrow passage way. They ambushed the Persian Navy. The Greeks had smaller more maneuverable ships and the Persians had huge ships. The Greeks ended sinking the Persians.