The Athenian generals seeing that some obstacle had arisen, and that the capture of the town by force was no longer practicable, at once proceeded to invest Nisaea, thinking that, if they could take it before relief arrived, the surrender of Megara would soon follow. Iron, stone-masons, and everything else required quickly coming up from Athens, the Athenians started from the wall which they occupied, and from this point built a cross wall looking towards Megara down to the sea on either side of Nisaea; the ditch and the walls being divided among the army, stones and bricks taken from the suburb, and the fruit-trees and timber cut down to make a palisade wherever this seemed necessary; the houses also in the suburb with the addition of battlements sometimes entering into the fortification. The whole of this day the work continued, and by the afternoon of the next the wall was all but completed, when the garrison in Nisaea, alarmed by the absolute want of provisions, which they used to take in for the day from the upper town, not anticipating any speedy relief from the Peloponnesians, and supposing Megara to be hostile, capitulated to the Athenians on condition that they should give up their arms, and should each be ransomed for a stipulated sum; their Lacedaemonian commander, and any others of his countrymen in the place, being left to the discretion of the Athenians. On these conditions they surrendered and came out, and the Athenians broke down the long walls at their point of junction with Megara, took possession of Nisaea, and went on with their other preparations. 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.