Thucydides, History of the Peloponnesian War
Benjamin Jowett, Ed.

91. 'You have heard the objects of our expedition from him who knows them best; the generals who remain will persevere and carry them out if they can. And now let me prove to you that if you do not come to the rescue Sicily will¹ be lost. [2] If the Greeks would all unite they might even now, notwithstanding their want of military skill, resist with success; but the Syracusans alone, whose whole forces have been already defeated, and who cannot move freely at sea, will be unable to withstand the power which the Athenians already have on the spot. [3] And Syracuse once taken, the whole of Sicily is in their hands; the subjugation of Italy will follow; and the danger which, as I was saying, threatens you from that quarter, will speedily overwhelm you. And therefore remember every one of you that the safety, not of Sicily alone, but of Peloponnesus, is at stake. [4] No time should be lost. You must send to Sicily a force of hoplites who will themselves handle the oars and will take the field immediately on landing. A Spartan commander I conceive to be even more indispensable than an army; his duty will be to organise the troops which are already enlisted, and to press the unwilling into the service. Thus you will inspire confidence in your friends and overcome the fears of the wavering. Here too in Hellas you should make open war. The Syracusans, seeing that you have not forgotten them, will then persevere in their resistance, while the Athenians will have greater difficulty in reinforcing their army. [5] You ought also to fortify Decelea in Attica; the Athenians are always in particular dread of this; [6] to them it seems to be the only peril of which they have not faced the worst in the course of the war. And the way to hurt an enemy most surely is to inform yourself exactly about the weak points of which you see that he is conscious, and strike at them. For every man is likely to know best himself the dangers which he has most to fear. I will sum up briefly the chief though by no means all the advantages which you will gain, and the disadvantages which you will inflict, by the fortification of Decelea. [7] The whole stock of the country will fall into your hands. The slaves will come over to you of their own accord; what there is besides will be seized by you. The Athenians will at once be deprived of the revenues which they obtain from the silver mines of Laurium, and of all the profits which they make by the land or by the law courts: above all, the customary tribute will cease to flow in; for their allies, when they see that you are now carrying on the war in earnest, will not mind them.