History of the Peloponnesian War

But the Chians and Erythraeans, they also desiring to revolt, went not to Agis, but to the Lacedaemonians in the city; and with them went also an ambassador from Tissaphernes, lieutenant to king Darius in the low countries of Asia. For Tissaphernes also instigated the Peloponnesians and promised to pay their fleet.

For he had lately begged of the king the tribute accruing in his own province; for which he was in arrearage, because he could receive nothing out of any of the Greek cities by reason of the Athenians. And therefore he thought by weakening the Athenians to receive his tribute the better, and withal to draw the Lacedaemonians into a league with the king; and thereby, as the king had commanded, to kill or take alive Amorges, Pissuthnes' bastard son, who was in rebellion against him about Caria. The Chians, therefore, and Tissaphernes followed this business jointly.