Aye Haggis. I wish to complement you on your knowledge. It doesn't seem to be a well known story and I don't understand why it does not receive more attention.
The story was recorded by Herodotus a Greek himself, so…
"In 480 B.C. the Persian Empire under King Xerxes, marched to invade Greece. The invading force numbered approximately 2 million (recorded by Herodotus). More modern estimates number the invaders from 150,000 to 180,000.
A force of three hundred Spartans was dispatched to the pass of Thermopylae, where the geography of the land favored a defending force. It was hoped, an elite force willing to sacrifice their lives could stall the invaders for a few days until the city states of Greece could muster its armies.
The defenders, led by a Spartan King named Leonidas held off the invaders for seven days.
Two memorials remain today at Thermopylae. Upon the modern one, called the Leonidas Monument is engraved his response to Xerxes' demand that the Spartans lay down their arms.
Leonidas' reply was two words, “Molon labe” which translates to “Come and get them.”