The Platæans who were not in the plot, imagined the force by which their city had been surprised to be much stronger than it really was, and, as no hostile treatment was offered to them, remained quiet, and entered into a parley with the Thebans. In the course of these conferences they gradually discovered that the number of the enemy was small, and might be easily overpowered; and, as they were in general attached to the Athenians, or at least strongly averse to an alliance with Thebes, they resolved to make the attempt, while the darkness might favour them, and perplex the strangers. To avoid suspicion they met to concert their plan of operation by means of passages opened through the walls of their houses; and having barricaded the streets with wagons, and made such other preparations as they thought necessary, a little before daybreak they suddenly fell upon the Thebans.
The little band made a vigorous defence, and twice or thrice repulsed the assailants; but as these still returned to the charge, and were assisted by the women and slaves, who showered stones and tiles from the houses on the enemy, all at the same time raising a tumultuous clamour, and a heavy rain increased the confusion caused by the darkness, they at length lost their presence of mind, and took to flight. But most were unable to find their way in the dark through a strange town, and several were slain as they wandered to and fro in search of an outlet. The gate by which they were admitted had in the meanwhile been closed, and no other was open. Some, pressed by their pursuers, mounted the walls, and threw themselves down on the outside, but for the most part were killed by the fall. A few were fortunate enough to break open one of the gates in a lone quarter, with an axe which they obtained from a woman, and to effect their escape. The main body, which had kept together, entered a large building adjoining the walls, having mistaken its gates, which they found open, for those of the town, and were shut in. The Platæans at first thought of setting fire to the building; but at length the men within, as well as the rest of the Thebans who were still wandering up and down the streets, surrendered at discretion.
Before their departure from Thebes it had been concerted that as large a force as could be raised should march the same night to support them. The distance between the two places was not quite nine miles, and these troops were expected to reach the gates of Platæa before the morning; but the Asopus, which crossed their road, had been swollen by the rain, and the state of the ground and the weather otherwise retarded them, so that they were still on their way when they heard of the failure of the enterprise. Though they did not know the fate of their countrymen, as it was possible that some might have been taken prisoners, they were at first inclined to seize as many of the Platæans as they could find without the walls, and to keep them as hostages. The Platæans anticipated this design, and were alarmed, for many of their fellow citizens were living out of the town in the security of peace, and there was much valuable property in the country. They therefore sent a herald to the Theban army to complain of their treacherous attack, and call upon them to abstain from further aggression, and to threaten that, if any was offered, the prisoners should answer for it with their lives. The Thebans afterwards alleged that they had received a promise, confirmed by an oath, that, on condition of their retiring from the Platæan territory, the prisoners should be released; and Thucydides seems disposed to believe this statement. The Platæans denied that they had pledged themselves to spare the lives of the prisoners, unless they should come to terms on the whole matter with the Thebans; but it does not seem likely that, after ascertaining the state of the case, the Thebans would have been satisfied with so slight a security. It is certain however that they retired, and that the Platæans, as soon as they had transported their movable property out of the country into the town, put to death all the prisoners—amounting to 180, and including Eurymachus, the principal author of the enterprise, and the man who possessed the greatest influence in Thebes.
On the first entrance of the Thebans into Platæa a messenger had been despatched to Athens with the intelligence, and the Athenians had immediately laid all the Bœotians in Attica under arrest; and when another messenger brought the news of the victory gained by the Platæans, they sent a herald to request that they would reserve the prisoners for the disposal of the Athenians. The herald came too late to prevent the execution: and the Athenians, foreseeing that Platæa would stand in great need of defence, sent a body of troops to garrison it, supplied it with provisions, and removed the women and children and all persons unfit for service in a siege.
After this event it was apparent that the quarrel could only be decided by arms. Platæa was so intimately united with Athens, that the Athenians felt the attack which had been made on it as an outrage offered to themselves, and prepared for immediate hostilities. Sparta, too, instantly sent notice to all her allies to get their contingents ready by an appointed day for the invasion of Attica. Two-thirds of the whole force which each raised were ordered to march, and when the time came assembled in the isthmus, where King Archidamus put himself at their head. An army more formidable, both in numbers and spirit, had never issued from the peninsula; and Archidamus thought it advisable, before they set out, to call the principal officers together, and to urge the necessity of proceeding with caution and maintaining exact discipline, as soon as they should have entered the enemy’s territory; admonishing them not to be so far elated by their superior numbers as to believe that the Athenians would certainly remain passive spectators of their inroads. And though all except himself were impatient to move, he would not yet take the decisive step, without making one attempt more to avert its necessity. He still cherished a faint hope, that the resolution of the Athenians might be shaken by the prospect of the evils of war which were now so imminent, and he sent Melesippus to sound their disposition. But the envoy was not able to obtain an audience from the people, nor so much as to enter the walls. A decree had been made, at the instigation of Pericles, to receive no embassy from the Spartans while they should be under arms. Melesippus was informed that if his government wished to treat with Athens, it must first recall its forces. He himself was ordered to quit Attica that very day, and persons were appointed to conduct him to the frontier, to prevent him from holding communication with any one by the way. On parting with his conductors he exclaimed, “This day will be the beginning of great evils to Greece.”
Such a prediction might well occur to any one, who reflected on the nature of the two powers which were now coming into conflict, and on the great resources of both, which, though totally different in kind, were so evenly balanced that no human eye could perceive in which scale victory hung; and the termination of the struggle could seem near only to one darkened by passion. The strength of Sparta, as was implied in the observation of Sthenelaidas, lay in the armies which she could collect from the states of her confederacy. The force which she could thus bring into the field is admitted by Pericles, in one of the speeches ascribed to him by Thucydides, to be capable of making head against any that could be raised by the united efforts of the rest of Greece. Within the isthmus her allies included all the states of Peloponnesus, except Achaia and Argos; and the latter was bound to neutrality by a truce which still wanted several years of its term. Hence the great contest now beginning was not improperly called the Peloponnesian War. Beyond the isthmus she was supported by Megara and Thebes, which drew the rest of Bœotia along with it; and Attica would thus have been completely surrounded on the land side by hostile territories, if Platæa and Oropus had not been politically attached to it. The Locrians of Opus, the Dorians of the mother-country, and the Phocians (though these last were secretly more inclined to the Athenians, who had always taken their part in their quarrels with Delphi, the stanch friend of Sparta) were also on her side. Thessaly, Acarnania, and the Amphilochian Argos, were in alliance with her enemy; but for this very reason, and more especially from their hostility to the Messenians of Naupactus, the Ætolians were friendly to her; and she could also reckon on the Corinthian colonies, Anactorium, Ambracia, and Leucas.
The power which Sparta exerted over her allies was much more narrowly limited than that which Athens had assumed over her subjects. The Spartan influence rested partly on the national affinity by which the head was united to the Dorian members of the confederacy, but still more on the conformity, which she established or maintained among all of them, to her own oligarchical institutions. This was the only point in which she encroached on the independence of any. Every state had a voice in the deliberations by which its interests might be affected; and if Sparta determined the amount of the contributions required by extraordinary occasions, she was obliged carefully to adjust it to the ability of each community. So far was she from enriching herself at the expense of the confederacy, that at the beginning of the war there was, as we have seen, no common treasure belonging to it, and no regular tribute for common purposes. But, to compensate for these defects, her power stood on a more durable basis of goodwill than that of Athens; and though in every state there was a party attached to the Athenian interest on political grounds, yet on the whole the Spartan cause was popular throughout Greece; and while Athens was forced to keep a jealous eye on all her subjects, and was in continual fear of losing them, Sparta, secure of the loyalty of her own allies, could calmly watch for opportunities of profiting by the disaffection of those of her rival.
At home indeed her state was far from sound, and the Athenians were well aware of her vulnerable side; but abroad, and as chief of the Peloponnesian confederacy, she presented the majestic and winning aspect of the champion of liberty against Athenian tyranny and ambition: and hence she had important advantages to hope from states which were but remotely connected with her, and were quite beyond the reach of her arms. Many powerful cities in Italy and Sicily were thus induced to promise her their aid, and it was on this she founded her chief expectations of forming a navy, which might face that of Athens. Her allies in this quarter engaged to furnish her with money and ships, which, it was calculated, would amount to no less than five hundred, though for the present it was agreed that they should wear the mask of neutrality, and admit single Athenian vessels into their ports. But as she was conscious that she should still be deficient in the sinews of war, she already began to turn her eyes to the common enemy of Greece, who was able abundantly to supply this want, and would probably be willing to lavish his gold for the sake of ruining Athens, the object of his especial enmity and dread.
The extent of the Athenian empire cannot be so exactly computed. In the language of the comic stage, it is said to comprehend a thousand cities; and it is difficult to estimate what abatement ought to be made from this playful exaggeration. The subjects of Athens were in general more opulent than the allies of Sparta, and their sovereign disposed of their revenues at her pleasure. The only states to which she granted more than a nominal independence were some islands in the western seas, Corcyra, Zacynthus, and Cephallenia—points of peculiar importance to her operations and prospects in that quarter, though even there she was more feared than loved. At the moment of the revolt of Potidæa her empire had reached its widest range, and her finances were in the most flourishing condition; and at the outbreak of the war her naval and military strength was at its greatest height. Pericles, as one of the ten regular generals, or ministers of war, before the Peloponnesian army had reached the frontier, held an assembly, in which he gave an exact account of the resources which the republic had at her disposal.
Her finances, beside the revenue which she drew from a variety of sources, foreign and domestic, were nourished by the annual tribute of her allies, which now amounted to six hundred talents [£120,000 or $600,000]. Six thousand, in money, still remained in the treasury, after the great expenditure incurred on account of the public buildings, and the siege of Potidæa, before which the sum had amounted to nearly ten thousand. But to this, Pericles observed, must be added the gold and silver which, in various forms of offerings, ornaments, and sacred utensils, enriched the temples or public places, which he calculated at five hundred talents, without reckoning the precious materials employed in the statues of the gods and heroes. The statue of Athene in the Parthenon alone contained forty talents’ weight of pure gold, in the ægis, shield, and other appendages. If they should ever be reduced to the want of such a supply, there could be no doubt that their tutelary goddess would willingly part with her ornaments for their service, on condition that they were replaced at the earliest opportunity.