Leonidas marched his army to meet Xerxes I at Thermopylae
Explanation:
The army of Xerxes 1 had been near Sparta and there was little support that they had gathered for themselves in these trying times.
Thus there was need for a great fight to be put up to stop the Persian onslaught of the Spartans who had come there to fight them and had stalled their progress enough to gather the soldiers for the war.
This has been the case in the first Persian invasion that had in this case largely failed and it did succeed in the later attempts.
