History of the Peloponnesian War

In this way Brasidas stole a rapid march through Thessaly, before any one was prepared to stop him, and reached Perdiccas and Chalcidice.

For what brought the army up out of the Peloponnese, while the affairs of Athens were so prosperous, was the fear of the Thrace-ward cities which had revolted from the Athenians, and that of Perdiccas:

the Chalcidians thinking that the Athenians would in the first place march against them, (and moreover, the cities near to them which had not revolted, secretly joined in the invitation,) and Perdiccas, though not an open enemy, yet being afraid, on his part also, because of his old quarrels with the Athenians, and most of all being desirous of reducing to subjection Arrhibaeus, the king of the Lyncestians.