History of the Peloponnesian War

After this the Syracusans and their allies proceeded to build a single wall running upwards from the city across Epipolae at an angle with the Athenian wall, in order that the Athenians, if they could not prevent its completion, might no longer be able to wall them off.

By this time the Athenians had finished their wall next to the sea and had come up to the high ground; and Gylippus, since a certain part of the Athenian wall was weak, took his army by night and advanced against this.

But the Athenians, who happened to be bivouacking outside the walls, perceived this movement and advanced against him; and he, on observing this, quickly led his men back again. The Athenians accordingly built this part of the wall higher and kept guard there themselves;

but their allies they now disposed along the rest of the wall, at the points where they were each to keep guard. Nicias determined also to fortify the place called Plemmyrium, a headland opposite the city, which juts out in front of the Great Harbour and makes its entrance narrow. If this were fortified, it seemed to him that the bringing in of supplies would be an easier matter; for the Athenians could keep watch upon the harbour of the Syracusans at nearer range, and would not, as now, be obliged to put out against the enemy from the inner bay of the Great Harbour, should they show any activity with their fleet. And in general from now on he gave his attention more to naval warfare, seeing that matters on land were less hopeful for themselves, now that Gylippus had come.

Accordingly, taking over his ships and some troops he built three forts, in which most of the stores were deposited; and the large boats and the ships of war were now moored there.