History of the Peloponnesian War

Just at this time the Lacedaemonian Brasidas, son of Tellis, happened to be in the neighbourhood of Sicyon and Corinth, getting ready an army for Thrace. As soon as he heard of the capture of the walls, fearing for the Peloponnesians in Nisaea and the safety of Megara, he sent to the Boeotians to meet him as quickly as possible at Tripodiscus, a village so called of the Megarid, under Mount Geraneia, and went himself, with two thousand seven hundred Corinthian heavy infantry, four hundred Phliasians, six hundred Sicyonians, and such troops of his own as he had already levied, expecting to find Nisaea not yet taken.

Hearing of its fall (he had marched out by night to Tripodiscus), he took three hundred picked men from the army, without waiting till his coming should be known, and came up to Megara unobserved by the Athenians, who were down by the sea, ostensibly, and really if possible, to attempt Nisaea, but above all to get into Megara and secure the town. He accordingly invited the townspeople to admit his party, saying that he had hopes of recovering Nisaea.