The Lacedæmonians, under the command of Agis, entered the Argolid with the contingents of Bœotia, Megara, Corinth, Phlius, Pellene, and Tegea. The Argive general, cut off from the town by a clever manœuvre, proposed a truce which Agis accepted. This was not what was desired by the Athenians, who arrived shortly after, to the number of a thousand hoplites and three hundred horsemen; Alcibiades spoke in presence of the people of Argos and prevailed with them: the truce was broken, a march was made on Orchomenos and it was taken. The blame of the rupture fell on Agis. The Spartans, angry at his having given their enemies time to make this conquest, wished first to demolish his house and condemn him to a fine of a hundred thousand drachmæ; his prayers won his pardon; but it was determined that in future the kings of Sparta should be assisted in the war by a council of ten Spartans.
To repair his mistake, Agis went in search of the allies; he encountered them near Mantinea. “The two armies,” says Thucydides, “advanced against each other; the Argives with impetuosity, the Lacedæmonians slowly and, according to their custom, to the sound of a great number of pipes which beat time and kept them in line.” The Lacedæmonian left was driven in, but the right, commanded by the king, retrieved the fight and carried the day (418). This battle, which cost the allies eleven hundred men and the Spartans about three hundred, is regarded by Thucydides as the most important which the Greeks had fought for a long time. It restored the reputation of Sparta in the Peloponnesus, and in Argos the preponderance of the wealthy who suppressed the popular commune, put its leaders to death and made an alliance with Lacedæmon.
[418-416 B.C.]
This treaty broke up the confederation recently agreed on with Athens, Elis, and Mantinea. The last-named town even thought itself sufficiently endangered by the defection of Argos to consent to descend once more to the rank of an ally of the Spartans. A treaty, dictated by the latter, decreed that all the states, great and small, should be free and should keep their national laws with their independence. Sparta desired nothing but divisions and weakness round her. To the policy of concentration advocated by Athens, she opposed the policy of isolation which was to put all Greece at her feet, but would also afterwards place her, with Sparta herself, at the feet of Macedonia and of the Romans (417).
The victory of Agis was that of the oligarchy. At Sicyon, in Achaia, it again raised its head or established itself more firmly. We have just seen how it resumed power in Argos. But in that town, if we are to believe Pausanias, a crime analogous to those which founded the liberties of the people in Rome brought about the fall of the tyrants three months later. Expelled by an insurrection, the chief citizens retired to Sparta, whilst the people appealed to the Athenians, and men, women, and children laboured to join Argos with the sea by means of long walls. Alcibiades hurried thither with masons and carpenters to aid in the work; but the Lacedæmonians, under the guidance of the exiles, dispersed the workers. Argos, exhausted by these cruel discords, did not recover herself; and with her fell that idea of a league of secondary states which might perhaps have spared Greece many misfortunes by imposing peace and a certain caution on the two great states (417).
[416 B.C.]
The Athenians, who were acting weakly in Chalcidice, had recently lost two towns there and had seen the king of Macedon withdraw from their alliance; they resolved to avenge themselves for all their embarrassments on the Dorian island of Melos, which was insulting their maritime empire by its independence. At Naxos and Samos they had shown themselves merciful, because they were amongst the Ionians where they could reckon on a democratic party; at Melos, an outpost of the Dorians in the Cretan Sea, they were implacable because the blow struck at these islanders, faithful to their metropolis, was to find a mournful echo in Lacedæmon. A squadron of thirty-eight galleys summoned the town to submit, and on its refusal an army besieged it, took it, and exterminated all the adult male population. The women and children were sold (416). Before the attack a conference had taken place with the Melians.