What was the feat of the three hundred Spartans?

The leader of the Spartan army realized that the situation was hopeless and they could not win this war. But in Sparta, all the warriors were accustomed to the fact that it was impossible to retreat and always fought to the last drop of blood. Leonidas ordered the Greeks to disperse to their homes. And only three hundred Spartans remained for this battle. None of the soldiers of Sparta could afford to retreat without an order, otherwise he would then lose everything and be expelled in disgrace. As a result, a small army of Spartans fought against a large army of Greeks.