Yet for nine years more the war continued, with much the same succession of varying events as before. But during this period Sparta was learning an important lesson. If she would defeat Athens, she must learn how to win victories on sea as well as on land. After every defeat of a fleet she built and equipped another, and gradually grew stronger in ships, and her seamen more skilful and expert, until the old difference between Athenian and Spartan seamen ceased to exist. Persia also came to the aid of Sparta, supplied her with money, and enabled her to replace her lost ships with ever new ones, while the ship-building power of Athens declined. In 405 B.C. the crisis came. Athens was forced to depend solely for subsistence on her fleet. That gone, all would be gone. In the autumn of that year she had a fleet of one hundred and eighty triremes in the Hellespont, in the close vicinity of a Spartan fleet of about the same force, under an able admiral named Lysander. AEgospotami, or Goat's River (a name of fatal sound to all later Athenians), was the station of the Athenian fleet. That of Sparta lay opposite, across the strait, nearly two miles away. And now an interesting scene began. Every day the Athenian fleet crossed the strait and offered battle to the Spartans, daring them to come out from their sheltered position. And every day, when the Spartans had refused, it would go back to the opposite shore, where many of the men were permitted to land. Day by day this challenge was repeated, the Athenians growing daily more confident and more careless, and the crews dispersing in search of food or amusement as soon as they reached the shore. Lysander, meanwhile, fox-like, was on the watch. A scout-ship followed the enemy daily. At length, on the fifth day, when the Athenian ships had anchored, and the sailors had, as usual, dispersed, the scout-ship hoisted a bright shield as a signal. In an instant the fleet of Lysander, which was all ready, dashed out of its harbor, and rowed with the utmost speed across the strait. The Athenian commanders, perceiving too late their mistake, did their utmost to recall the scattered crews, but in vain. The Spartan ships dashed in among those of Athens, found some of them entirely deserted, others nearly so, and wrought with such energy that of the whole fleet only twelve ships escaped. Nearly all the men ashore were also taken, while this great victory was won not only without the loss of a ship, but hardly of a man. The prisoners, three or four thousand in number, in the cruel manner of the time, were put to death.