After this the Syracusans and their allies began to carry a single wall, starting from the city, in a slanting direction up Epipolae, in order that the Athenians, unless they could hinder the work, might be no longer able to invest them. Meanwhile the Athenians, having now finished their wall down to the sea, had come up to the heights; and part of their wall being weak, Gylippus drew out his army by night and attacked it. However, the Athenians who happened to be bivouacking outside took the alarm and came out to meet him, upon seeing which he quickly led his men back again. The Athenians now built their wall higher, and in future kept guard at this point themselves, disposing their confederates along the remainder of the works, at the stations assigned to them. Nicias also determined to fortify Plemmyrium, a promontory over against the city, which juts out and narrows the mouth of the Great Harbour. He thought that the fortification of this place would make it easier to bring in supplies, as they would be able to carry on their blockade from a less distance, near to the port occupied by the Syracusans; instead of being obliged, upon every movement of the enemy's navy, to put out against them from the bottom of the great harbour. Besides this, he now began to pay more attention to the war by sea, seeing that the coming of Gylippus had diminished their hopes by land. Accordingly, he conveyed over his ships and some troops, and built three forts in which he placed most of his baggage, and moored there for the future the larger craft and men-of-war. This was the first and chief occasion of the losses which the crews experienced. The water which they used was scarce and had to be fetched from far, and the sailors could not go out for firewood without being cut off by the Syracusan horse, who were masters of the country; a third of the enemy's cavalry being stationed at the little town of Olympieum, to prevent plundering incursions on the part of the Athenians at Plemmyrium. Meanwhile Nicias learned that the rest of the Corinthian fleet was approaching, and sent twenty ships to watch for them, with orders to be on the look-out for them about Locris and Rhegium and the approach to Sicily.
Gylippus, meanwhile, went on with the wall across Epipolae, using the stones which the Athenians had laid down for their own wall, and at the same time constantly led out the Syracusans and their allies, and formed them in order of battle in front of the lines, the Athenians forming against him. At last he thought that the moment was come, and began the attack; and a hand-to-hand fight ensued between the lines, where the Syracusan cavalry could be of no use; and the Syracusans and their allies were defeated and took up their dead under truce, while the Athenians erected a trophy. After this Gylippus called the soldiers together, and said that the fault was not theirs but his; he had kept their lines too much within the works, and had thus deprived them of the services of their cavalry and darters. He would now, therefore, lead them on a second time. He begged them to remember that in material force they would be fully a match for their opponents, while, with respect to moral advantages, it were intolerable if Peloponnesians and Dorians should not feel confident of overcoming Ionians and islanders with the motley rabble that accompanied them, and of driving them out of the country.
After this he embraced the first opportunity that offered of again leading them against the enemy. Now Nicias and the Athenians held the opinion that even if the Syracusans should not wish to offer battle, it was necessary for them to prevent the building of the cross wall, as it already almost overlapped the extreme point of their own, and if it went any further it would from that moment make no difference whether they fought ever so many successful actions, or never fought at all. They accordingly came out to meet the Syracusans.
Gylippus led out his heavy infantry further from the fortifications than on the former occasion, and so joined battle; posting his horse and darters upon the flank of the Athenians in the open space, where the works of the two walls terminated. During the engagement the cavalry attacked and routed the left wing of the Athenians, which was opposed to them; and the rest of the Athenian army was in consequence defeated by the Syracusans and driven headlong within their lines. The night following the Syracusans carried their wall up to the Athenian works and passed them, thus putting it out of their power any longer to stop them, and depriving them, even if victorious in the field, of all chance of investing the city for the future.
After this the remaining twelve vessels of the Corinthians, Ambraciots, and Leucadians sailed into the harbour under the command of Erasinides, a Corinthian, having eluded the Athenian ships on guard, and helped the Syracusans in completing the remainder of the cross wall. Meanwhile Gylippus went into the rest of Sicily to raise land and naval forces, and also to bring over any of the cities that either were lukewarm in the cause or had hitherto kept out of the war altogether. Syracusan and Corinthian envoys were also dispatched to Lacedaemon and Corinth to get a fresh force sent over, in any way that might offer, either in merchant vessels or transports, or in any other manner likely to prove successful, as the Athenians too were sending for reinforcements; while the Syracusans proceeded to man a fleet and to exercise, meaning to try their fortune in this way also, and generally became exceedingly confident.