History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
and as the Boeotians assisted them in their negotiations, Agis was persuaded to delay matters so far as the Euboeans were concerned and began arranging their revolt for the Lesbians, giving them as harmost Alcamenes, who was to have sailed to Euboea; furthermore, the Boeotians promised them ten ships and Agis the same number. These negotiations were carried on without the authority of the Lacedaemonian state;
for so long as he was stationed at Deceleia with his own force Agis possessed full power to send troops anywhere he wished as well as to levy them and to exact money. And at that time the allies hearkened to him far more, one might say, than to the Lacedaemonians in Sparta; for he had a force at his own disposal and his appearance anywhere instantly inspired fear. So he was working in the interest of the Lesbians, but the Chians[*](The oligarchs, as shown by chs. ix and xiv. Chios had hitherto been noted for its loyalty to Athens.) and Erythraeans, who also were ready to revolt, betook themselves, not to Agis, but to Lacedaemon.