In Sicily, about the same time in this spring, Gylippus came to Syracuse with as many troops as he could bring from the cities which he had persuaded to join. Calling the Syracusans together, he told them that they must man as many ships as possible, and try their hand at a sea-fight, by which he hoped to achieve an advantage in the war not unworthy of the risk. With him Hermocrates actively joined in trying to encourage his countrymen to attack the Athenians at sea, saying that the latter had not inherited their naval prowess nor would they retain it for ever; they had been landsmen even to a greater degree than the Syracusans, and had only become a maritime power when obliged by the Mede. Besides, to daring spirits like the Athenians, a daring adversary would seem the most formidable; and the Athenian plan of paralysing by the boldness of their attack a neighbour often not their inferior in strength could now be used against them with as good effect by the Syracusans. He was convinced also that the unlooked-for spectacle of Syracusans daring to face the Athenian navy would cause a terror to the enemy, the advantages of which would far outweigh any loss that Athenian science might inflict upon their inexperience. He accordingly urged them to throw aside their fears and to try their fortune at sea; and the Syracusans, under the influence of Gylippus and Hermocrates, and perhaps some others, made up their minds for the sea-fight and began to man their vessels.
When the fleet was ready, Gylippus led out the whole army by night; his plan being to assault in person the forts on Plemmyrium by land, while thirty-five Syracusan galleys sailed according to appointment against the enemy from the great harbour, and the forty-five remaining came round from the lesser harbour, where they had their arsenal, in order to effect a junction with those inside and simultaneously to attack Plemmyrium, and thus to distract the Athenians by assaulting them on two sides at once. The Athenians quickly manned sixty ships, and with twenty-five of these engaged the thirty-five of the Syracusans in the great harbour, sending the rest to meet those sailing round from the arsenal; and an action now ensued directly in front of the mouth of the great harbour, maintained with equal tenacity on both sides; the one wishing to force the passage, the other to prevent them.
In the meantime, while the Athenians in Plemmyrium were down at the sea, attending to the engagement, Gylippus made a sudden attack on the forts in the early morning and took the largest first, and afterwards the two smaller, whose garrisons did not wait for him, seeing the largest so easily taken. At the fall of the first fort, the men from it who succeeded in taking refuge in their boats and merchantmen, found great difficulty in reaching the camp, as the Syracusans were having the best of it in the engagement in the great harbour, and sent a fast-sailing galley to pursue them. But when the two others fell, the Syracusans were now being defeated; and the fugitives from these sailed alongshore with more ease. The Syracusan ships fighting off the mouth of the harbour forced their way through the Athenian vessels and sailing in without any order fell foul of one another, and transferred the victory to the Athenians; who not only routed the squadron in question, but also that by which they were at first being defeated in the harbour, sinking eleven of the Syracusan vessels and killing most of the men, except the crews of three ships whom they made prisoners. Their own loss was confined to three vessels; and after hauling ashore the Syracusan wrecks and setting up a trophy upon the islet in front of Plemmyrium, they retired to their own camp.
Unsuccessful at sea, the Syracusans had nevertheless the forts in Plemmyrium, for which they set up three trophies. One of the two last taken they razed, but put in order and garrisoned the two others.
In the capture of the forts a great many men were killed and made prisoners, and a great quantity of property was taken in all. As the Athenians had used them as a magazine, there was a large stock of goods and corn of the merchants inside, and also a large stock belonging to the captains; the masts and other furniture of forty galleys being taken, besides three galleys which had been drawn up on shore. Indeed the first and chiefest cause of the ruin of the Athenian army was the capture of Plemmyrium; even the entrance of the harbour being now no longer safe for carrying in provisions, as the Syracusan vessels were stationed there to prevent it, and nothing could be brought in without fighting; besides the general impression of dismay and discouragement produced upon the army.