After their defeat at the Battle of Marathon, the Persians, led by King Xeres, the son of Darius I, mounted a second invasion of Greece around 480 BC seeking revenge. The Greeks, led by the Spartan King Leonidas I and 300 Spartans, met the Persians at a narrow pass in the mountains called Thermopylae. The Greeks held off the Persians for 7 days until the Persians found a way around the mountains and got behind the Greeks. and annihilated them.
The Persian army then went to Athens and burned it. The Athenian fleet, was waiting for the Persians by the island of Salamis. The Athenian ships, called triremes, were fast and maneuverable. They rammed into the sides of the large Persian ships and sunk them. They defeated the Persians and Xerxes went back to Persia leaving his general Mardonius to finish the conquest.
The following spring, the Greeks assembled the largest army ever and attacked Mardonius at the Battle of Plataea. The Greeks won and killed Mardonius. On the same day, across the Aegean Sea, the Greek navy defeated the Persian navy at the Battle of Mycale. With this double defeat, the invasion was ended, and the Greeks expelled the Persians from Europe, the Aegean islands and Ionia before the war finally came to an end in 479 BC.