History of the Peloponnesian War

The Boeotians took the same time to assemble at Tanagra; and when all the forces were come in that from every city were expected, and when they understood that the Athenians drew homewards, though the rest of the Boeotian commanders, which were eleven, approved not giving battle, because they were not now in Boeotia (for the Athenians, when they laid down their arms, were in the confines of Oropia); yet Pagondas, the son of Aioladas, being the Boeotian commander for Thebes, whose turn it was to have the leading of the army, was, together with Arianthidas, the son of Lysimachidas, of opinion to fight, and held it the best course to try the fortune of a battle; wherefore calling them unto him every company by itself, that they might not be all at once from their arms, he exhorted the Boeotians to march against the Athenians and to hazard battle, speaking in this manner:

Men of Boeotia, it ought never to have so much as entered into the thought of any of us the commanders that, because we find not the Athenians now in Boeotia, it should therefore be unfit to give them battle. For they out of a bordering country have entered Boeotia and fortified in it with intent to waste it, and are indeed enemies in whatsoever ground we find them, or whencesoever they come doing the acts of hostility.

But now if any man think it also unsafe, let him henceforth be of another opinion. For providence, in them that are invaded, endureth not such deliberation concerning their own as may be used by them who, retaining their own, out of desire to enlarge, voluntarily invade the estate of another.

And it is the custom of this country of yours, when a foreign enemy comes against you, to fight with him both on your own and on your neighbour's ground alike; but much more you ought to do it against the Athenians when they be borderers.