History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
But after all was ready and when they were about to make their departure, the moon, which happened then to be at the full, was eclipsed.[*](August 27, 413 B.C.) And most of the Athenians, taking the incident to heart, urged the generals to wait. Nicias also, who was somewhat too much given to divination and the like, refused even to discuss further the question of their removal until they should have waited thrice nine days, as the soothsayers prescribed. Such, then, was the reason why the Athenians delayed and stayed on.
The Syracusans on their part, on learning about this, were far more aroused than before and determined not to give the Athenians any respite, seeing that these had now of their own act confessed themselves no longer superior either with their fleet or with their land-force, for otherwise they would not have laid plans for their departure; and at the same time, because they did not want them to settle down somewhere else in Sicily where it would be more difficult to carry on war against them, they were determined to force them to fight a sea-battle as quickly as possible on the spot, in a place that suited themselves.
Accordingly they regularly manned their ships and practised for as many days as they thought sufficient. Then, when the favourable moment came, they assaulted on the first day the Athenian walls, and when a small body of hoplites and of horsemen came out against them by certain gates, they cut off a number of the hoplites, and putting them to flight followed in pursuit; and as the entrance to the camp was narrow, the Athenians lost seventy horses and a few of the hoplites.
So on this first day the Syracusan army withdrew; but on the following day they sailed out with their ships, seventy-six in number, and at the same time advanced with their land-force against the walls. The Athenians put out to sea to meet them with eighty-six ships, and closing with them commenced the battle.