Thermopylae was some distance from Sparta but it was the ideal spot to hold off the Persians as it was only about 55 feet wide at its narrowest point with the sea on one side and soaring cliffs on the other. Sparta, however, did not want to march so far away from home, nor did they want to leave during a religious holiday. Leonidas was inspired by the message from the Oracle (which also happens to be the only verse worthy of posting) which said that the city would be lost if a King was not sacrificed (Sparta was ruled by two kings.) In the following verse the "He" in the second paragraph refers to Xerxes.
O ye men who dwell in the streets of broad Lacedaemon!Leonidas led his men knowing that no more reinforcements from Sparta would come to his aid. On the way others joined, for a total of maybe 5200 Greeks arrayed against a Persian army so large that one refered to them as drinking up entire rivers. Xerxes, wanting to prevent bloodshed (or perhaps further bloodshed) and thinking that he was dealing with reasonable men offered to spare their lives if they laid down their weapons. To this offer King Leonidas responded "Molon Labe" which means Come and get them. On the morning of the third day of battle, Xerxes had found a path through the mountains to flank the Spartans. Learning of this Leonidas ordered all of the troops back but his Spartans. However the Thespians, numbering approximately 700, stayed and went to meet the flanking troops. They made their final stand there at the pass of Thermopylae. Ctesias, a Greek historian, estimated 50,000 of Xerxes army were cut down over those 3 days.
Either your glorious town shall be sacked by the children of Perseus,
Or, in exchange, must all through the whole Laconian country
Mourn for the loss of a king, descendant of great Heracles.
He cannot be withstood by the courage of bulls nor of lions,
Strive as they may; he is mighty as Jove; there is naught that shall stay him,
Till he have got for his prey your king, or your glorious city.
The burial stone for these heroes reads (as translated by Michael Dodson)
Friend, tell the Spartans that on this hill
We lie obedient to them still.