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.

Meanwhile Gylippus, noticing that the Athenians on Plemmyrium had gone down to the sea and were giving their attention to the sea-fight, surprised them by making a sudden attack at daybreak upon the forts; and first he captured the largest, and afterwards the two smaller ones also, their garrisons not awaiting the attack when they saw the largest so easily taken.

Of the garrison of the fort that was taken first, all that succeeded in escaping to the boats and to a certain merchant ship were rescued and brought to camp, but it was with difficulty; for the Syracusans were at the time having the best of the fight with their ships in the Great Harbour, and a trireme, and that a fast sailer, was sent in pursuit. But when the other two forts were taken, the Syracusans, as it chanced, were by this time losing the fight, and those who fled from these forts had less difficulty in sailing past them.