The Eight Books of Thucydides' History, translated by R. Crawley.
The same summer the Athenian general, Demosthenes, arrived at Naupactus with forty ships immediately after the return from the Megarid. Hippocrates and himself had had overtures made to them by certain men in the cities in Boeotia, who wished to change the constitution and introduce a democracy as at Athens; Ptoeodorus, a Theban exile, being the chief mover in this intrigue. The seaport town of Siphae, in the bay of Crisae, in the Thespian territory, was to be betrayed to them by one party; Chaeronea (a dependency of what was formerly called the Minyan, now the Boeotian, Orchomenus) to be put into their hands by another from that town, whose exiles were very active in the business, hiring men in Peloponnese. Some Phocians also were in the plot, Chaeronea being the frontier town of Boeotia and close to Phanotis in Phocia. Meanwhile the Athenians were to seize Delium, the sanctuary of Apollo, in the territory of Tanagra looking towards Euboea; and all these events were to take place simultaneously upon a day appointed, in order that the Boeotians might be unable to unite to oppose them at Delium, being everywhere detained by disturbances at home. Should the enterprise succeed, and Delium be fortified, its authors confidently expected that even if no revolution should immediately follow in Boeotia, yet with these places in their hands, and the country being harassed by incursions, and a refuge in each instance near for the partisans engaged in them, things would not remain as they were, but that the rebels being supported by the Athenians and the forces of the oligarchs divided, it would be possible after a while to settle matters according to their wishes.
Such was the plot in contemplation. Hippocrates with a force raised at home awaited the proper moment to take the field against the Boeotians; while he sent on Demosthenes with the forty ships above mentioned to Naupactus, to raise in those parts an army of Acarnanians and of the other allies, and sail and receive Siphae from the conspirators; a day having been agreed on for the simultaneous execution of both these operations. Demosthenes on his arrival found Oeniadae already compelled by the united Acarnanians to join the Athenian confederacy, and himself raising all the allies in those countries marched against and subdued Salynthius and the Agraeans; after which he devoted himself to the preparations necessary to enable him to be at Siphae by the time appointed.
Reference address : https://www.ellopos.net/elpenor/greek-texts/ancient-greece/thucydides/history-4.asp?pg=42