History of the Peloponnesian War

Phrynichus now saw that there would be a proposal to restore Alcibiades, and that the Athenians would consent to it; and fearing after what he had said against it that Alcibiades, if restored, would revenge himself upon him for his opposition, had recourse to the following expedient. He sent a secret letter to the Lacedaemonian admiral,

Astyochus, who was still in the neighbourhood of Miletus, to tell him that Alcibiades was ruining their cause by making Tissaphernes the friend of the Athenians, and containing an express revelation of the rest of the intrigue, desiring to be excused if he sought to harm his enemy even at the expense of the interests of his country.

However, Astyochus, instead of thinking of punishing Alcibiades, who, besides, no longer ventured within his reach as formerly, went up to him and Tissaphernes at Magnesia, communicated to them the letter from Samos, and turned informer, and if report may be trusted, became the paid creature of Tissaphernes, undertaking to inform him as to this and all other matters; which was also the reason why he did not remonstrate more strongly against the pay not being given in full.

Upon this Alcibiades instantly sent to the authorities at Samos a letter against Phrynichus, stating what he had done, and requiring that he should be put to death.

Phrynichus distracted, and placed in the utmost peril by the denunciation, sent again to Astyochus, reproaching him with having so ill kept the secret of his previous letter, and saying that he was now prepared to give them an opportunity of destroying the whole Athenian armament at Samos; giving a detailed account of the means which he should employ, Samos being unfortified, and pleading that being in danger of his life on their account, he could not now be blamed for doing this or anything else to escape being destroyed by his mortal enemies. This also Astyochus revealed to Alcibiades.