The Athenian fleet now arrived and blockaded the city; after several little engagements the Mytileneans were reduced to extremities. Their envoys had at length prevailed upon the Peloponnesians to send them a motley fleet to relieve Mytilene. But it set sail with the usual slowness of the Spartans, and did not arrive until Mytilene, compelled by famine, had surrendered. Such was the care shown to save Mytilene! The long endurance of famine, shows how strongly the Mytileneans were bent upon escaping from the dominion of their enemies. How fearful it must have been, may be inferred from the fact, that in the end they preferred surrendering at discretion to an enraged enemy. The courage of the Mytileneans was like that of the Campanians in the Hannibalic War: they allowed themselves to be shut up like sheep in a fold, to be starved, and thus there remained nothing for them in the end, but to surrender. Many of those who had been most conspicuous, were taken prisoners by Paches, the Athenian general. The capitulation contained nothing else but a promise that the Athenian commander would not, on his own authority, order any one to be put to death, and that he would leave the decision to the people of Athens.
The war had already assumed the most fearful character: Alcidas, the Spartan admiral of the Peloponnesian fleet, which went to the relief of the Mytileneans, had, on his voyage, indulged in the most cruel piracy; he had captured all the ships he met with, without any regard as to what place they belonged to, and had thrown into the sea the crews of the allies and subjects of the Athenians, for whose deliverance the Spartans pretended to be anxious, as well as those of Athenian vessels. This barbarous mode of warfare was practised by the Spartans from the very beginning of the war. They not only captured the Athenian ships which sailed round Peloponnesus, but mutilated the crews, chopping off the hands of the sailors, and then drowned them.
This inhuman cruelty of the Spartans excited in the minds of the Athenians a desire to make reprisals; and thus it unfortunately became quite a natural feeling among the Athenians to devise inhuman vengeance upon the Mytileneans. They felt that Athens had given the Mytileneans no cause for revolt, that the alliance with them had been left unaltered as it had been before, and that if the Mytileneans had succeeded in joining the Spartans, they would have brought Athens into great danger, partly by their power, and partly by their example. It was, moreover, thought necessary to terrify Chios by a striking example, in order that the oligarchical party there might not attempt a similar undertaking. Those who did not see the necessity for such a measure, at least imagined that they saw it, for reasons of this kind are never anything else than an evil pretext. With all enticements of this description, the people were induced to despatch orders to the general Paches to avenge on the Mytileneans what the Spartans had done to the Athenians. He was to put to death all the men capable of bearing arms, and to sell women and children into slavery.
But the minds of the Athenians were too humane for such a design to be entertained by them for any length of time; and although it had been possible to carry out such a decree, through the existing confusion of ideas about morality, yet the better voice had not yet died away in their bosoms. The historian need not tell us that thousands could not close their eyes during the night in consequence of the terrible decree; and that through fear lest it should be carried into effect, they assembled early in the morning, even before sunrise. The morning after the day on which the decree had been passed, all the people met earlier than usual, and demanded of the prytanes once more to put the question to the vote, to see whether the decree should be carried into effect or not. This was done, and although the ferocious Cleon struggled with all fury to obtain the sanction of the first decree, yet humanity prevailed at this second voting.
It is in this debate that Cleon first appears in the pages of Thucydides; he was opposed by Diodotus who, by calm logic rather than impassioned appeal, won the Athenians over to mercy. It is thus that Thucydides describes the escape of the Mytileneans: