Its great error, however, was an attempt at foreign conquest, when it had quite enough to occupy it at home. War broke out between Athens and Sicily, and a strong fleet was sent to blockade and seek to capture the city of Syracuse. This expedition fatally sapped the strength of the Athenian empire. Ships and men were supplied in profusion to take part in a series of military blunders, of which the last were irreparable. The fleet, with all on board, was finally blocked up in the harbor of Syracuse, defeated in battle, and forced to yield, while of forty thousand Athenian troops but a miserable remnant survived to end their lives as slaves in Syracusan quarries. It was a disaster such as Athens in its whole career had not endured, and whose consequences were inevitable. From that time on the supremacy of Athens was at an end.
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. Ægospotami, 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.
This defeat, so disgraceful to the Athenian commanders, so complete and thorough, was a death-blow to the dominion of Athens. That city was left at the mercy of its foes. When news of the disaster reached the city, such a night of wailing and woe, of fear and misery, came upon the Athenians as few cities had ever before gone through. Their fleet gone, all was gone. On it depended their food. Their land-supplies had long been cut off. No corn-ships could now reach them from the Euxine Sea, and few from other quarters. They might fight still, but the end was sure. The victor at Salamis would soon be a prisoner within her own walls.
Lysander was in no hurry to sail to Athens. That city could wait. He employed himself in visiting the islands and cities in alliance with or dependent upon Athens, and inducing them to ally themselves with Sparta. The Athenian garrisons were sent home. Lysander shrewdly calculated that the more men the walls of Athens held, the sooner must their food-supply be exhausted and the end come. At length, in November of 405 B.C., Lysander sailed with his fleet to Piræus and blockaded its harbor, while the land army of the Peloponnesus marched into Attica and encamped at the gates of Athens.
That great and proud city was now peopled with despair. The plague which had desolated it twenty-five years before now threatened to be succeeded by a still more fatal plague, that of famine. Yet pride and resolution remained. The walls had been strengthened; their defenders could hold out while any food was left; not until men actually began to die of hunger did they ask for peace.
The envoys sent to Sparta were refused a hearing. Athens wished to preserve her walls. Sparta sent word that there could be no peace until the Long Walls were levelled with the earth. These terms Athens proudly refused. Suffering and privation went on.
For three months longer the siege continued. Though famine dwelt within every house, and numbers died of starvation, the Athenians held out with heroic endurance, and refused to surrender on humiliating terms. But there could be only one end. Where famine commands man must obey. Peace must be had at any price, or death would end all, and an envoy was sent out with power to make peace on any terms he could obtain.