In the July which followed the treaty with Argos, the Olympic games, which recurred every fourth year, were to be celebrated. The Athenians had been shut out by the war from the two previous celebrations; and curiosity was excited throughout Greece to see what figure Athens would make at this great Pan-Hellenic festival. War, it was surmised, must have exhausted her resources, and would thus prevent her from appearing with becoming splendour. But from this reproach she was rescued by the wealth and vanity, if not by the patriotism, of Alcibiades. By his care, the Athenian deputies exhibited the richest display of golden ewers, censers, and other plate to be used in the public sacrifice and procession; whilst for the games he entered in his own name no fewer than the unheard-of number of seven four-horsed chariots, of which one gained the first, and another the second prize. Alcibiades was consequently twice crowned with the olive, and twice proclaimed victor by the herald.

The growing ambition and success of Alcibiades prompted him to carry his schemes against Sparta into the very heart of Peloponnesus, without, however, openly violating the peace.

The Lacedaemonians now found it necessary to act with more vigour; and accordingly in B.C. 418 they assembled a very large army, under the command of the Spartan king, Agis. A decisive battle was fought near Mantinea, in which Agis gained a brilliant victory over the Argives and their allies. This battle and that of Delium were the two most important engagements that had yet been fought in the Peloponnesian war. Although the Athenians had fought on the side of the Argives at Mantinea, the peace between Sparta and Athens continued to be nominally observed.

In B.C. 416 the Athenians attacked and conquered Melos, which island and Thera were the only islands in the AEgean not subject to the Athenian supremacy. The Melians having rejected all the Athenian overtures for a voluntary submission, their capital was blockaded by sea and land, and after a siege of some months surrendered. On the proposal, as it appears, of Alcibiades, all the adult males were put to death, the women and children sold into slavery, and the island colonized afresh by 500 Athenians. This horrible proceeding was the more indefensible, as the Athenians, having attacked the Melians in full peace, could not pretend that they were justified by the custom of war in slaying the prisoners. It was the crowning act of insolence and cruelty displayed during their empire, which from this period began rapidly to decline.

The event destined to produce that catastrophe--the intervention of the Athenians in the affairs of Sicily--was already in progress. A quarrel had broken out between Egesta and Selinus, both which cities were seated near the western extremity of Sicily; and Selinus, having obtained the aid of Syracuse, was pressing very hard upon the Egestaeans. The latter appealed to the interests of the Athenians rather than to their sympathies. They represented how great a blow it would be to Athens if the Dorians became predominant in Sicily, and joined the Peloponnesian confederacy; and they undertook, if the Athenians would send an armament to their assistance, to provide the necessary funds for the prosecution of the war. Their most powerful advocate was Alcibiades, whose ambitious views are said to have extended even to the conquest of Carthage. The quieter and more prudent Nicias and his party threw their weight into the opposite scale. But the Athenian assembly, dazzled by the idea of so splendid an enterprise, decided on despatching a large fleet under Nicias, Alcibiades, and Lamachus, with the design of assisting Egesta, and of establishing the influence of Athens throughout Sicily, by whatever means might be found practicable.

For the next three months the preparations for the undertaking were pressed on with the greatest ardour. Young and old, rich and poor, all vied with one another to obtain a share in the expedition. Five years of comparative peace had accumulated a fresh supply both of men and money; and the merchants of Athens embarked in the enterprise as in a trading expedition. It was only a few of the wisest heads that escaped the general fever of excitement, The expedition was on the point of sailing, when a sudden and mysterious event converted all these exulting feelings into gloomy foreboding.

At every door in Athens, at the corners of streets, in the market place, before temples, gymnasia, and other public places, stood Hermae, or statues of the god Hermes, consisting of a bust of that deity surmounting a quadrangular pillar of marble about the height of the human figure. When the Athenians rose one morning towards the end of May, 415 B.C., it was found that all these figures had been mutilated during the night, and reduced by unknown hands to a shapeless mass. The act inspired political, as well as religious, alarm. It seemed to indicate a widespread conspiracy, for so sudden and general a mutilation must have been the work of many hands. The sacrilege might only be a preliminary attempt of some powerful citizen to seize the despotisn, and suspicion pointed its finger at Alcibiades. Active measures were taken and large rewards offered for the discovery of the perpetrators. A public board was appointed to examine witnesses, which did not, indeed, succeed in eliciting any facts bearing on the actual subject of inquiry, but which obtained evidence respecting similar acts of impiety committed at previous times in drunken frolics. In these Alcibiades himself was implicated; and though the fleet was on the very eve of departure, a citizen rose in the assembly and accused Alcibiades of having profaned the Eleusinian mysteries by giving a representation of them in a private house, producing in evidence the testimony of a slave. Alcibiades denied the accusation, and implored the people to have it investigated at once. His enemies, however, had sufficient influence to get the inquiry postponed till his return; thus keeping the charge hanging over his head, and gaining time to poison the public mind against him.

The Athenian fleet, consisting of 100 triremes, and having on board 1500 chosen Athenian hoplites, as well as auxiliaries, at length set sail, and proceeded to Corcyra, where it was joined by the other allies in the month of July, 415 B.C. Upon arriving at Rhegium the generals received the discouraging news that Egesta was unable to contribute more than thirty talents. A council of war was now held; and it was finally resolved to gain as many allies as they could among the Greek cities in Sicily, and, having thus ascertained what assistance they could rely upon, to attack Syracuse and Selinus.