Yes this a repeat of a previous question, but I could not figure out how to post this answer, so I shall try to re-ask the question and answer it myself:
Book V Chapter XVII: "Sixteenth Year of the War—The Melian Conference—Fate of Melos"
is known as the Melian Dialogue, and is one of the most famous portions of one of the greatest books of antiquity.
Wikipedia describes it under the heading "Melian Dialogue" as follows:
"The Melian dialogue takes place fifteen years into the Peloponnesian war, during the confrontation in 416–415 BC between the Athenians and the people of Melos, a small island located in the southern Aegean Sea just east of Sparta. The Athenians demanded that the Melians surrender their city and pay them tribute or face the destruction of their city. The Melians claimed their right to remain neutral, appealing to the Athenians' sense of decency and mercy toward a small, peaceful, and defenseless city."
The Athenians said to the Melians:
"you know as well as we do that right, as the world goes, is only in question between equals in power, while the strong do what they can and the weak suffer what they must."
The Melians refused to surrender, so the Athenians defeated them, killed the adult men, and sold the women and children into slavery.