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

11. 'Athenians, in many previous despatches I have reported to you the course of events up to this time, but now there is greater¹ need than ever that you should inform yourselves of our situation, and come to some decision. [2] After we had engaged the Syracusans, against whom you sent us, in several battles, and conquered in most of them, and had raised the lines within which we are now stationed, Gylippus a Lacedaemonian arrived, bringing an army from Peloponnesus and from certain of the cities of Sicily. In the first engagement he was defeated by us, but on the following day we were overcome by numerous horsemen and javelin-men, and retired within our lines. [3] We have therefore desisted from our siege-works and remain idle, since we are overpowered by the superior numbers of the enemy, and indeed cannot bring our whole army into the field, for the defence of our wall absorbs a large part of our heavy-armed. The enemy meanwhile have built a single wall which crosses ours, and we cannot now invest them, unless a large army comes up and takes this crosswall. [4] So that we, who are supposed to be the besiegers, are really the besieged², at least by land; and the more so because we cannot go far even into the country, for we are prevented by their horsemen.