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.
Meanwhile the Athenians who had been despatched in the hundred ships around the Peloponnesus, together with the Corcyraeans, who had reinforced them with fifty ships, and some of their other allies in that quarter, were pillaging various places as they cruised about, and in particular disembarked at Methone in Laconia and assaulted its walls, which were weak and without adequate defenders.
But Brasidas, son of Tellis, a Spartan, happened to be in that neighbourhood with a guarding party, and seeing the situation he set out with one hundred hoplites to relieve the garrison. Dashing through the army of the Athenians, which was scattered over the country and was occupied solely with the fortress, he threw his force into Methone, losing a few of his men in the rush, and thus saved the city. This daring exploit, the first of the kind in the war, was acknowledged at Sparta by a vote of thanks.