History of the Peloponnesian War

On the same day, too, an Athenian trireme that was keeping watch at the mouth of the Great Harbour was captured by the Syracusans.

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;