Phœbidas fell in with the proposed plot, and the day of the feast of the Thesmophoria was appointed for its execution. On that day the women of the city celebrated by themselves a festival in the ancient temple of Demeter on the Cadmea. Phœbidas was to make a feint of striking camp and setting out on his march northwards. While the council was assembled in a hall in the market-place and the heat of noon-day kept the rest of the population indoors, Leontiades galloped after the departing general, led him unobserved up to the citadel, and opened the gates to him. He then hied to the council, announced what had taken place, and had Ismenias arrested as a seditious person. The leaders and adherents of the opposition, to the number of three hundred, were obliged to flee for their lives to Athens. The occupation of the Cadmea was a political necessity, the logical consequence of the efforts of Sparta to secure the hegemony. The experiences of the last war had not been suffered in vain.
While Agesilaus was pursuing his victorious career in Asia a coalition against Sparta had been formed in Greece at the instigation of Persia, and Thebes had shown herself most zealous in promoting this anti-Spartan combination which was so grave a menace to the existence of Lacedæmon. This time Sparta was once more undertaking a war on the confines of Greece; if fortune were adverse, if a battle were lost, she had no guarantee against the possibility—the probability even—that hostile Thebes, still barely subdued, might revolt again, bar the way of retreat against the Spartan army, and throw the most serious obstacles in the way of reinforcements. “The Cadmea was the decisive point for the security of the line of march,” says Curtius. If a prolonged war were to be waged in the distant north it was essential that this position should be in friendly hands. And the only way of attaining this object was to juggle the reins of government into the hands of the oligarchical party in Thebes and to garrison the citadel with Spartan hoplites for their protection. The success of the expedient proves how well worth while it had been for Phœbidas to take the circuitous route.
This act of violence, the surprise of the Theban citadel in time of peace, called forth a storm of indignation throughout the whole of Greece. Even in Sparta itself a clamour of popular displeasure arose against Phœbidas, because (as Xenophon adds) he had acted without due warrant or command. Apparently the Spartan government found it expedient to cast the odium of the proceeding upon Phœbidas, and therefore, in spite of Xenophon’s silence on the subject, there is probably some truth in the story that he was deposed from his command and condemned to pay an exorbitant fine. The wrath of Greece may well have been the reason for this mock sentence. The payment of the fine was never exacted, and in the following year he held the office of a Spartan harmost in Bœotia. For the rest, the remonstrances of Leontiades and Agesilaus, the latter of whom openly maintained that the only point to be considered in judging the case was whether the transgression of Phœbidas were profitable to the state or not, quickly persuaded the Spartans of the propriety and necessity of the coup-de-main. The citadel was not evacuated, and legal proceedings were taken against Ismenias in respect of the league. A solemn tribunal was called together in Thebes, consisting of three Spartan commissioners and a deputy from every town of the league, to pass judgment upon the crimes of Ismenias. He was condemned to death. The most repulsive feature of this judicial murder, which was merely an act of vengeance upon the whilom leader of the anti-Spartan coalition, is the farce of a tribunal which was supposed to represent national ideas and interests.
The road to Thrace was now safe, and the war against Olynthus was prosecuted with the utmost vigour.