History of the Peloponnesian War

When the fleet was ready, Gylippus led out his whole land-force under cover of night, intending in person to make an assault by land upon the forts of Plemmyrium, and at the same time, on a preconcerted signal, thirty-five Syracusan triremes sailed to the attack from the Great Harbour, while forty-five sailed round from the lesser harbour, where their ship-yard was, purposing to form a junction with those inside the harbour and simultaneously attack Plemmyrium, so that the Athenians, thus assailed from both directions, might be thrown into confusion.

But the Athenians, hastily manning sixty ships to oppose them, with twenty-five engaged the thirty-five Syracusan ships that were in the Great Harbour, and with the rest went to meet the squadron that was sailing round from the ship-yard. And so they at once engaged in battle in front of the mouth of the Great Harbour, and for a long time held out against one another, one side wishing to force the entrance, the other to prevent this.

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.