History of the Peloponnesian War

The Athenian generals were aware of all this and purposed to draw the whole of the Syracusan force as far as possible away from the city, and themselves meanwhile to sail down under cover of night and undisturbed to occupy a camp at a suitable place, knowing that they would not be able to do this so well if they should disembark from their ships in the face of an enemy prepared to meet them, or should be detected going by land. For being without horsemen themselves, their own light-armed troops and their mob of camp-followers would, they thought, suffer great harm at the hands of the numerous Syracusan cavalry; but in the way proposed they would take a position where they would not suffer any harm worth mentioning from the cavalry; and certain Syracusan exiles who were with them gave them information as to the position close to the Olympieium, which in fact they subsequently occupied. So then, in furtherance of their plan, the generals devised some such scheme as this:

They sent a man loyal to themselves, but in the opinion of the Syracusan generals no less a friend of theirs. The man was a Catanaean, and said that he had come from men at Catana whose names they recognized and whom they knew to be the remnant of those who were still loyal to them in the city.

He said that the Athenians were in the habit of passing the night in the city away from their arms, and if the Syracusans would come in full force at dawn on an appointed day against their army, they would close the gates on the Athenians in their city and set fire to the ships, and the Syracusans could attack the stockade and easily take the whole army; for there were many Catanaeans who would help them in this undertaking, and the men from whom he himself had come were ready now.