History of the Peloponnesian War

The base from which they started was Eion, their commercial seaport at the mouth of the river, not more than three miles from the present town, which Hagnon named Amphipolis, because the Strymon flows round it on two sides, and he built it so as to be conspicuous from the sea and land alike, running a long wall across from river to river, to complete the circumference.

Brasidas now marched against this town, starting from Arne in Chalcidice. Arriving about dusk at Aulon and Bromiscus, where the lake of Bolbe runs into the sea, he supped there, and went on during the night.

The weather was stormy and it was snowing a little, which encouraged him to hurry on, in order, if possible, to take every one at Amphipolis by surprise, except the party who were to betray it.

The plot was carried on by some natives of Argilus, an Andrian colony, residing in Amphipolis, where they had also other accomplices gained over by Perdiccas or the Chalcidians.

But the most active in the matter were the inhabitants of Argilus itself, which is close by, who had always been suspected by the Athenians, and had had designs on the place. These men now saw their opportunity arrive with Brasidas, and having for some time been in correspondence with their countrymen in Amphipolis for the betrayal of the town, at once received him into Argilus, and revolted from the Athenians, and that same night took him on to the bridge over the river;