18. In the mean time the Greeks were preparing for the onset. Sparta, true to her military organization, did little but to bring her army to the perfection of discipline, and many of the weaker cities resolved to quietly submit to the invaders. The Athenians alone seemed to have fully understood the gravity of the situation. To them the rage of the Persian king was particularly directed, for the crushing defeat at Marathon, and Athens was more exposed than any other of the Greek cities. During the ten years Athens raised and equipped as large an army as her population would warrant. Every able-bodied man was enrolled in the ranks. Food and military stores were collected, but the chief means of defense was a novel one, and showed the desperate nature of the conflict in which they were about to engage. Under the wise direction of Themistocles they built a formidable fleet, so large that in case of emergency the whole population of the city could embark, and either remain afloat or take refuge on the neighboring islands. 19. A congress of the cities had determined to oppose the approach of Xerxes at some favorable place by a combined army. At the head of the Maliac gulf there was a narrow pass, through which the Persians had to go, the road running between a mountain and a swamp which stretched to the sea; and at one place the swamp came so near the mountain that there was hardly room for the road to run between. This is the famous pass of Thermopylæ; and here it was that a small army might block the way against any number of the enemy. Across this pass a wall was built, and behind it was posted the Greek army under the command of Leonidas, the Spartan king. His forces consisted of three hundred Spartans, seven hundred Thespians, and about four thousand more from the various Grecian cities. The Persians approached, and for four days waited, expecting to see the Greek army disperse at the very sight of their formidable numbers. But as they were apparently not frightened, on the fifth day the Persians made an attack. For two days the battle continued, inflicting great losses upon the Persians, while the little army of Leonidas, behind their fortifications, was scarcely injured. 20. On the third morning a renegade Greek showed Xerxes a path across the mountains where he could completely turn the Greek position. The Persians were not slow to avail themselves of this intelligence, and toward the close of the third day Leonidas saw the enemy descending the mountain, ready to surround him and cut off his retreat. Acting promptly, he ordered his allies to leave the field before it was too late, but he, with his devoted band of three hundred, were to remain, in accordance of a Spartan law which forbade a Spartan soldier ever to retreat from the presence of an enemy. The seven hundred Thespians remained with him, and the whole band was cut down, but not without inflicting fearful loss upon the enemy. [Illustration: THERMOPYLAE (Map)]