History of the Peloponnesian War

In this manner Brasidas ran through Thessaly before any there could put in readiness to stop him and came into the territory of the Chalcideans and to Perdiccas.

For Perdiccas and the Chalcideans, all that had revolted from the Athenians, when they saw the affairs of the Athenians prosper, had drawn this army out of Peloponnesus for fear; the Chalcideans, because they thought the Athenians would make war on them first, as having been also incited thereto by those cities amongst them that had not revolted; and Perdiccas, not that he was their open enemy, but because he feared the Athenians for ancient quarrels, but principally because he desired to subdue Arrhibaeus, king of the Lyncesteans.

And the ill success which the Lacedaemonians in these times had was a cause that they obtained an army from them the more easily.