What was the feat of the 300 Spartans?

The legendary feat of Tsar Leonidas and his soldiers will forever remain in history as an example of valor and self-sacrifice for the sake of a common cause. The Battle of Thermopylae took place in 480 BC between the Greeks under the leadership of the Spartans and the army of the Persians of King Xerxes. The backbone of the Hellenes consisted of 300 citizens of Sparta – the elite of the infantry in ancient Greece. The army of the Greeks numbered from 5000 to 7700 thousand hoplites, and the enemy – about 200 thousand. The battle lasted 3 days and ended with the defeat of the Spartans because of the betrayal of Ephialtes. Despite this, their death was not in vain. She debunked the myth of the invincibility of the Persians and raised the morale of the Greeks before the main battles of that war.