All, however, was of no avail. When night came the Immortals were compelled to withdraw, and leave the Greeks in possession of their intrenchments.
Things continued substantially in this state for one or two days longer, when one morning a Greek countryman appeared at the tent of Xerxes, and asked an audience of the king. He had something, he said, of great importance to communicate to him. The king ordered him to be admitted. The Greek said that his name was Ephialtes, and that he came to inform the king that there was a secret path leading along a wild and hidden chasm in the mountains, by which he could guide a body of Persians to the summit of the hills overhanging the pass at a point below the Greek intrenchment. This point being once attained, it would be easy, Ephialtes said, for the Persian forces to descend into the pass below the Greeks, and thus to surround them and shut them in, and that the conquest of them would then be easy. The path was a secret one, and known to very few. He knew it, however, and was willing to conduct a detachment of troops through it, on condition of receiving a suitable reward.
The king was greatly surprised and delighted at this intelligence. He immediately acceded to Ephialtes's proposals, and organized a strong force to be sent up the path that very night.
On the north of Thermopylæ there was a small stream, which came down through a chasm in the mountains to the sea. The path which Ephialtes was to show commenced here, and following the bed of this stream up the chasm, it at length turned to the southward through a succession of wild and trackless ravines, till it came out at last on the declivities of the mountains near the lower part of the pass, at a place where it was possible to descend to the defile below. This was the point which the thousand Phocæans had been ordered to take possession of and guard, when the plan for the defense of the pass was first organized. They were posted here, not with the idea of repelling any attack from the mountains behind them--for the existence of the path was wholly unknown to them--but only that they might command the defile below, and aid in preventing the Persians from going through, even if those who were in the defile were defeated or slain.