History of the Peloponnesian War

Considering himself therefore to be in every way slighted by them, he both spoke against the treaty in the first instance, saying that the Lacedaemonians were not to be depended upon, but were only making a treaty in order that by so doing they might deprive Athens of the Argives. and again come against them when left alone; and at that time, when this difference had arisen, he immediately sent to Argos on his own account, urging them to come as quickly as possible with proposals for alliance, in company with the Mantineans and Eleans, since it was a fine opportunity, and he would co-operate with them to the utmost.

When the Argives received this message, and found that the alliance with the Boeotians had not been brought about in concert with the Athenians, but that they were involved in a serious quarrel with the Lacedaemonians; they thought no more of their ambassadors at Lacedaemon, who were just at that time gone thither on the subject of the treaty, but paid more attention to the Athenians; thinking that so, if they went to war, there would be on their side in it a state which had been their friend from of old, and was under a democratical form of government, like themselves, and wielded a great power in the command of the sea.