History of the Peloponnesian War

Then revolted to him Myrcinus, a city of the Edonians, Pittacus, the king of the Edonians, being slain by the sons of Goaxis and by Braures his own wife. And not long after Gapselus also, and Oesyme, colonies of the Thasians. Perdiccas also, after the taking of these places, came to him and helped him in assuring of the same.

After Amphipolis was taken, the Athenians were brought into great fear, especially for that it was a city that yielded them much profit, both in timber which is sent them for the building of galleys and in revenue of money, and because also, though the Lacedaemonians had a passage open to come against their confederates, the Thessalians convoying them, as far as to Strymon, yet if they had not gotten that bridge, the river being upwards nothing but a vast fen, and towards Eion well guarded with their galleys, they could have gone no further; which now they thought they might easily do, and therefore feared lest their confederates should revolt.