History of the Peloponnesian War

About the same period, in the beginning of this winter, Sitalces son of Teres, the king of the Odrysian Thracians, made an expedition against Perdiccas, son of Alexander, king of Macedonia, and the Thrace-ward Chalcidians; of two promises wishing to enforce the one, and himself to perform the other.

For Perdiccas had made him certain promises if he would effect a reconciliation between him and the Athenians, when he was hard pressed by the war at its commencement, and if he would not restore his brother Philip, who was at enmity with him, to place him on the throne; but he was not disposed to perform what he had promised. On the other hand, Sitalces had pledged himself to the Athenians, when he entered into alliance with them, to bring the Chalcidian war in Thrace to a successful issue.

It was with both these objects then that he made the invasion; in which he took with him Philip's son Amyntas, to set him on the throne of Macedonia, and some envoys from Athens, who happened to be at his court on this business, and Hagnon as commander; for the Athenians also were to join him against the Chalcidians with a fleet, and as large an army as they could raise.