History of the Peloponnesian War

And the Plataeans, when they became aware that the Thebans were inside, and that the city had been taken by surprise, took fright, and, as it was night and they could not see, thinking that a far greater number had come in, they concluded to make terms, and, accepting the proposals made to them, raised no disturbance, especially as the Thebans did no violence to anyone.

But, as it happened, while they were negotiating the terms they perceived that the Thebans were few in number, and thought that by an attack they might easily overpower them; for it was not the wish of the majority of the Plataeans to withdraw from the Athenian alliance.

So it was determined to make the attempt, and they began to collect together, reaching each other's houses by digging through the party-walls that they might not be seen going through the streets, and they placed wagons without the draught-animals in the streets to serve as a barricade, and took other measures as each appeared likely to be advantageous in the present emergency.

And when all was ready as far as they could make it so, waiting for the time of night just before dawn, they sallied from their houses against the Thebans, not wishing to attack them by day when they might be more courageous and would be on equal terms with them, but at night when they would be more timid and at a disadvantage, in comparison with their own familiarity with the town. And so they fell upon them at once, and speedily came to close quarters.