On the banks of the Strymon, just where the river sweeps round in a sharp curve, west and east, the Athenians had founded, six years before the outbreak of the war, the colony of Amphipolis. It was a site which had long been coveted by the leaders of Greek colonial enterprise, being the key to the richest district in Thrace, with unrivalled facilities for commerce, and close to the gold-mines of Mount Pangeus. A previous attempt which was made by the Athenians to occupy the position had ended in ruinous disaster; but nearly thirty years later a second body of emigrants, led by Hagnon from Athens, met with much better success; Amphipolis now grew and prospered, and at the time which we have reached was the most important city in the Athenian empire. The Amphipolitans had a bitter and jealous enemy in the neighbouring town of Argilus, situated a few miles to the west, on the road to Amphipolis; and ever since the appearance of Brasidas in Thrace the Argilians had been plotting against the tranquillity of their hated rival. Accordingly, when Brasidas, who had planned a surprise on Amphipolis, appeared before their gates, they welcomed him eagerly, and conducted him and his army to the bridge over the Strymon, which crossed the river just outside the southern end of the city wall. The defenders of the bridge, few in number, and taken unawares, were instantly cut to pieces; for Brasidas came upon them before daybreak, and the weather, which was wintry and inclement, favoured his design. The farms and country-houses of the Amphipolitans, which occupied an extensive district on the eastern side of the city, now lay at the mercy of Brasidas, and after choosing a position for his camp, he began to overrun the country. For those who were responsible for the safety of Amphipolis had taken no precautions, though they knew that this daring and active enemy had been carrying on a campaign for many weeks in the adjacent parts of Thrace. Consequently, a good number of the citizens, who were attending to the business of their estates, fell into his hands, and it is not improbable that, if he had made a sudden assault on the city, he would have captured it on the same day.