History of the Peloponnesian War

For each side expected that a battle would be fought between the Athenians and those who had come to relieve the place, and that so it would be safer for themselves to go over to the side they favoured, if it were victorious. When therefore Brasidas did not prevail on them, he returned again to the rest of the army.

In the morning the Boeotians joined them, having indeed purposed, even before Brasidas sent to them, to march to the relief of Megara, considering the danger to affect themselves, and being already in full force at Plataea; but when the messenger reached them, they felt much more confidence, and after despatching two thousand two hundred heavy-armed, and six hundred cavalry, they returned again with the main force.

When the whole army was now come, amounting to no less than six thousand heavy-armed, and when the Athenian heavy-armed were formed in line about Nisaea at the shore, but their light-armed were dispersed over the plain; the Boeotian horse fell upon the light-armed, and drove them to the sea, while they were not expecting it; for before this no succours had yet come to the Megareans from any quarter.

But the Athenian horse charged in return, and came to close quarters with them; and there was a cavalry action which lasted for a long time, in which both parties claim to have had the better.

For the Athenians, close under the walls of Nisaea, charged, killed, and stripped the Boeotian commander of the horse, and some few others; and having got possession of these bodies, restored them under truce, and elected a trophy: yet, regarding the action as a whole, neither party retired with a decided result, but the Boeotians drew off to their forces, and the Athenians to Nisaea.