History of the Peloponnesian War

And on that occasion the cart was already at the gates, and on their being opened in the usual manner for the skiff, as they thought, the Athenians, (for this had been done by agreement with them,) on seeing it, ran full speed from their ambush, wishing to reach the spot before the gates were shut again, and while the cart was still in the entrance, and prevented their being closed; the Megareans who were in concert with them at the same time dispatching the guard at the gate.

Demosthenes with his Plataeans and peripoli were the first to run in, (at the point where the trophy now stands,) and as soon as they were within the wall, (for now the nearest Peloponnesians were aware of it,) the Plataeans engaged with and defeated those who came to the rescue, and secured the gates for the advancing heavy-armed of the Athenians.

Then each of the Athenians, as he successively entered, proceeded against the wall.

And of the Peloponnesian garrison a few at first resisted, and defended themselves, and some of them were killed; but the greater part took to flight, being terrified in consequence of the enemy having attacked them by night, and the Megarean traitors fighting against them; and thinking that all the Megareans had betrayed them.

For it happened that the Athenian herald had of his own accord proclaimed, that whoever of the Megareans wished, should go and pile his arms with the Athenians. So when they heard that, they stayed no longer; but thinking that they were certainly the objects of a common attack, fled for refuge to Nisaea.

In the morning, when the walls were now taken, and the Megareans in the city were in confusion, those who had negotiated with the Athenians, and others with them, viz. the popular party who were privy to the measure, said that they ought to throw open the gates, and march out to battle. It had been arranged by them, that when the gates were opened, the Athenians should rush in;

and they themselves would be distinguished from the rest, for they said they would anoint themselves with oil, that they might not be hurt. And they felt the greater security in opening the gates, since, according to agreement, the four thousand Athenian heavy-armed from Eleusis, and six hundred horse, had marched all night, and were now there.