Every night for a long time back, under pretence of marauding, in order to have a means of opening the gates, they had been used, with the consent of the officer in command, to carry by night a sculling boat upon a cart along the ditch to the sea, and so to sail out, bringing it back again before day upon the cart, and taking it within the wall through the gates, in order, as they pretended, to baffle the Athenian blockade at Minoa, there being no boat to be seen in the harbour.

On the present occasion the cart was already at the gates, which had been opened in the usual way for the boat, when the Athenians, with whom this had been concerted, saw it, and ran at the top of their speed from the ambush in order to reach the gates before they were shut again, and while the cart was still there to prevent their being closed; their Megarian accomplices at the same moment killing the guard at the gates.

The first to run in was Demosthenes with his Plataeans and Peripoli, just where the trophy now stands; and he was no sooner within the gates than the Plataeans engaged and defeated the nearest party of Peloponnesians who had taken the alarm and come to the rescue, and secured the gates for the approaching Athenian heavy infantry.
After this, each of the Athenians as fast as they entered went against the wall.

A few of the Peloponnesian garrison stood their ground at first, and tried to repel the assault, and some of them were killed; but the main body took fright and fled; the night attack and the sight of the Megarian traitors in arms against them making them think that all Megara had gone over to the enemy.

It so happened also that the Athenian herald of his own idea called out and invited any of the Megarians that wished, to join the Athenian ranks; and this was no sooner heard by the garrison than they gave way, and, convinced that they were the victims of a concerted attack, took refuge in Nisaea.