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.
For all these reasons, and because at that time Deceleia was doing them much injury and the general expenses which were accruing were very great, they became crippled in the matter of money; and it was at this time that they imposed upon their subjects, instead of a tribute, a duty of five per cent. on all commodities imported or exported by sea, thinking that in this way they should derive more revenue. For their expenses were not on the same scale as before, but had become far heavier, in proportion as the war had become greater, and their revenues were steadily failing.
As for the Thracians,[*](cf. xxvii. 1.) then, who had come too late for Demosthenes, the Athenians immediately sent them back, being unwilling on account of the present shortage of money to incur expense; and they commissioned Dieitrephes to conduct them, giving him instructions to use them, as he sailed along the coast (for they would go by way of the Euripus), in doing whatever damage he could to the enemy.
So he disembarked them in the territory of Tanagra and made a hasty raid; then he sailed immediately after nightfall from Chalcis in Euboea across the Euripus and landing the Thracians in Boeotian territory led them against Mycalessus.