History of the Peloponnesian War

The summer following, the truce for a year, which was to last till the Pythian holidays, expired. During this truce, the Athenians removed the Delians out of Delos, because [though they were consecrated, yet] for a certain crime committed of old they esteemed them polluted persons; because also they thought there wanted this part to make perfect the purgation of the island, in the purging whereof, as I declared before, they thought they did well to take up the sepulchres of the dead. These Delians seated themselves afterwards, every one as he came, in Adramyttium in Asia, a town given unto them by Pharnaces.

After the truce was expired, Cleon prevailed with the Athenians to be sent out with a fleet against the cities lying upon Thrace. He had with him of Athenians twelve hundred men of arms and three hundred horsemen, of confederates more, and thirty galleys.