WHY THE 300 : Battle of Thermopylae

The disproportionate losses of the Persian army alarmed Xerxes so that when his navy was later defeated at the Salamis he fled Greece leaving only part of his force to finish the job of the conquest of Greece, that was defeated at the battle of Plataea. The performance of the defenders at the battle of Thermopylae is often used as an example of the advantages of training, equipment and good use of terrain to maximise an army's potential, as well as a symbol of courage against extremely overwhelming odds. The heroic sacrifice of the Spartans and the Thespians has captured the minds of many throughout the ages and has given birth to many cultural references as a result.
There is an epitaph on a monument at site of the battle (which was erected in 1955) with Simonides' epigram, which can be found in Herodotus' work The Histories (7.228), to the Spartans:
Ω ξειν', αγγέλλειν Λακεδαιμονίοις ότι τάδε
(O xein', angellein Lakedaimoniois hoti têde)
κείμεθα τοις κείνων ρήμασι πειθόμενοι.
(keimetha tois keinon rhémasi peithomenoi.)
Which to keep the poetic context can be translated as:
Go tell the Spartans, stranger passing by,
that here, obedient to their laws, we lie
Herodotus wrote that when Dienekes, a Spartan soldier, was informed that Persian arrows were so numerous that they blotted out the sun, he remarked with characteristically laconic prose,
"So much the better, we shall fight in the shade."