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.
and the land-force at the same time withdrew from the walls. On the next day the Syracusans kept quiet, giving no indication of what they would do next. Nicias, on the other hand, seeing that the issue of the sea-fight had been a draw and expecting the enemy to attack again, compelled the trierarchs to repair their ships, in case any had suffered damage, and anchored merchant-ships in front of the Athenian stockade, which had been planted in the sea in front of their ships to serve in place of an enclosed harbour.
These merchant-ships he placed at intervals of about two hundred feet from one another, in order that any ships which should be hard pressed might find safe refuge inside and again sail out at leisure. In these preparations the Athenians spent the whole day until nightfall.