The Melian dialogue, contained in Thucydides's History of the Peloponnesian War, is an account of the confrontation in 416–415 BC, between the Athenians and the people of Melos, a small island in the southern Aegean Sea. Melos was a neutral island, lying just east of Sparta; the Athenians wanted to conquer the island to intimidate the Spartans. In general, "the Dialogue is formally not about the morality of the eventual execution, but about the Melian response to the Athenians' first demand, that Melos should submit."
The historical background of this portion of the History of the Peloponnesian War is the invasion of the island of Melos by Athens in 416 BC during a brief lull in the Peloponnesian War. Just after the Battle of Mantinea in 417 BC, the Athenians moved on the Melians and demanded that they join the Delian League, thus effectively becoming part of their empire. The Melians had always resisted the influence of the Delian League, and resisted this invasion as well. Thucydides created the Dialogue in order to represent the actual events of the Athenians speaking to the Melians. His use of speeches in The History of the Peloponnesian War allowed readers to understand the way in which Athens created their empire. The Athenians sent the League's fleet to Melos to await the time to attack if Melos did not come to a peaceful agreement to surrender to the Athenian representatives.
The Athenians, in a frank and matter-of-fact manner, offer the Melians an ultimatum: surrender and pay tribute to Athens, or be destroyed.
The Melians argue that they are a neutral city and not an enemy, so Athens has no need to crush them. The Athenians counter that, if they accept the Melians' neutrality and independence, they would look weak: people would think they spared Melos because they were not strong enough to conquer it.
The Melians argue that an invasion will alarm the other neutral Greek states, who will become hostile to Athens for fear of being invaded themselves. The Athenians counter that the Greek states on the mainland are unlikely to act this way. It is the more volatile island states and the subjects they have already conquered that are more likely to take up arms against Athens.
The Melians argue that it would be shameful and cowardly of them to submit without a fight. In Thucydides' account, "If such hazards are taken by you to keep your empire and by your subjects to escape it, we who are still free would show ourselves great cowards and weaklings if we failed to face everything that comes rather than submit to slavery." The Athenians counter that the debate is not about honour but about self-preservation.
The Melians argue that though the Athenians are far stronger, there is still a chance they could win. The Athenians counter that only the strong have a right to indulge in hope; the weak Melians are hopelessly outnumbered.
The Melians state that they also refuse because they believe they have the assistance of the gods. Thucydides recounts, "We trust that the gods will give us fortune as good as yours, because we are standing for what is right against what is wrong." The Athenians counter that gods and men alike respect strength over moral arguments, summarising this in the famous dictum that, "The strong do as they can and the weak suffer what they must".
The Melians insist that their Spartan kin will come to their defence. The Athenians argue that the Spartans have nothing to gain and a lot to lose by coming to the Melians' aid – mere kinship will not motivate them.
The Athenians then conclude the argument by saying there is no shame in submitting to a stronger enemy. The Melians do not change their minds and politely dismiss the envoys.
The Melian Dialogue opened up many arguments about the morality of destroying Melos. One of the arguments in the Melian Dialogue is whether or not the destruction of Melos was a humanitarian act. The destruction of Melos was not humanitarian, but the Athenians' attempts to procure the surrender of Melos before destroying it was at the least less inhumane than an immediate debellation would have been. A.B. Bosworth represents both points of view. He argues that the Melian Dialogue was not humanitarian at all because of the brutality the Athenians used against Melos. However, he also argues that it could be humanitarian because, "they could only confront them with the reality of their position in the bluntest terms. Harsh their language undoubtedly is, but it has a humanitarian end, to convince the Melian oligarchs of the need to capitulate and save themselves and the commons the horrors of a siege." The Melians were put in quite the predicament: to save themselves and surrender or have their nation completely destroyed for the sake of independence.
As for Thucydides' point of view, it would seem that he may have had a bias in favour of the Melians because of his exile from Athens. W. Liebeschuetz argues that the Athenians were "wrong and deluded" because of their lack of morality in Melos' destruction but also that "the Athenians were also perfectly right that the Melians' own interest required that they should yield to the Athenians since they had not the strength to resist successfully." However, D.M. Lewis declares that, "Thucydides, with his strong feeling for the power and glory of Athens, may have seen this differently and regarded the Melians' heroics as foolish and unrealistic; and the fact that they had been offered a relatively painless alternative might affect his view of the massacre." Lewis also questioned how much of a reaction Thucydides wanted to get from his readers, based on the cruelty the Athenians showed the Melians. This was because "judgments about the Athenian empire is certainly in large part due to the attention that Thucydides' Dialogue has focused on it, but the feeling he displays elsewhere about that empire makes it questionable if he intended to produce the revulsion which most readers of the Dialogue feel." The Melian Dialogue garners a lot more attention in The History of the Peloponnesian War because of Athens' hostility than Thucydides might have intended.
Though they were faced with overwhelming odds, the Melians believed that the Spartans, who were their kin, would come to their aid against Athens. Moreover, they did not want to be regarded as cowards for surrendering so easily and submitting themselves to dominance by Athens.
The dialogue does not reflect the Melians' making any appeal to the potential counter-argument that Athens' allowing the Melians to remain neutral, simply continuing its empire-building around them while they did as they pleased, would show strength rather than weakness by demonstrating that Athens was so powerful that it and its empire would not suffer and had nothing to fear even if the Melians refused to cooperate.
Ultimately, Melos refused to surrender to the Athenians. The Athenians immediately besieged Melos, as threatened. Thucydides writes, "Our decision, Athenians, is just the same as it was at first. We are not prepared to give up in a short moment the liberty which our city has enjoyed from its foundation for 700 years." With this decision, the Athenians now had the excuse they needed to destroy Melos, even though the Melians offered them peace at the end of the Dialogue by saying, "‘We invite you to allow us to be friends of yours and enemies to neither side, to make a treaty which shall be agreeable to both you and us, and so to leave our country.'" Although the Melians held out for a time, the Athenians eventually won after some form of unspecified treachery within the city. They then proceeded to execute all the men they took captive and enslaved the women and children, and further, repopulated it as an Athenian colony.
Liebeschuetz notes an irony in the Melian Dialogue: "The Athenians look at the present and can see nothing will save Melos. They are right. The Melians look to the future. They are right too. Melos is destroyed. But the very next sentence in the history begins the story of the decline of Athens and the justification of the Melians." This is incredible because both groups, the Melians and Athenians, predicted outcomes that both came to pass at a later time. Athens correctly predicted that Sparta would not or could not prevent the Athenian army from destroying Melos. Yet the Melians were also correct in their belief in their kindred, the Spartans. After the fall of their city, the surviving Melians were resettled on the mainland by Sparta. Within a few years the Peloponnesian War resumed between Sparta and Athens, and the Melian community in exile raised funds to contribute to the Spartan war effort, which successfully destroyed the Athenian empire. The Spartan general Lysander then retook Melos and restored the Melians to their homeland. Overall, Melos was one of the few islands in the Cyclades that stood up for itself despite the negative repercussions.
Seaman notes the irony of the fall of Melos: "It is indeed ironic to consider that it was in fact her longstanding neutrality which left Melos as prey for Athens during the Peace of Nicias."
- Athenian: "For ourselves, we shall not trouble you with specious pretenses—either of how we have a right to our empire because we overthrew the Mede, or are now attacking you because of wrong that you have done us—and make a long speech which would not be believed; and in return we hope that you, instead of thinking to influence us by saying that you did not join the Spartans, although their colonists, or that you have done us no wrong, will aim at what is feasible, holding in view the real sentiments of us both; since 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" (5.89).
- Melians: "You may be sure that we are as well aware as you of the difficulty of contending against your power and fortune, unless the terms be equal. But we trust that the gods may grant us fortune as good as yours, since we are just men fighting against unjust, and that what we want in power will be made up by the alliance of the Lacedaemonians, who are bound, if only for very shame, to come to the aid of their kindred. Our confidence, therefore, after all is not so utterly irrational."
- Athenian: "Of the gods we believe, and of men we know, that by a necessary law of their nature they rule wherever they can. And it is not as if we were the first to make this law, or to act upon it when made: we found it existing before us, and shall leave it to exist forever after us; all we do is to make use of it, knowing that you and everybody else, having the same power as we have, would do the same as we do" (5.105.2).
See also 
- D.M., Lewis. The Cambridge Ancient History Vol. V. (Cambridge: Cambridge University Press, 1992), 444.
- Thucydides. History of the Peloponnesian War. (London: Penguin Books Ltd, 1972), 400.
- Thucydides, Peloponnesian War, 403
- Thucydides, Peloponnesian War, 404.
- A. B. Bosworth (1993). "The humanitarian aspect of the Melian Dialogue". The Journal of Hellenic Studies 113: 30–44. JSTOR 632396.
- W. Liebeschuetz (1968). "The structure and function of the Melian Dialogue". The Journal of Hellenic Studies 88: 73–77. JSTOR 628672.
- Lewis, Cambridge Ancient History, 445.
- Lewis, Cambridge Ancient History, 446.
- Thucydides, Peloponnesian War, 407.
- Seaman, Michael G., "The Athenian Expedition to Melos in 416 B.C.," Historia 46 (1997) pp. 418.
- Robert B. Strassler, The Landmark Thucydides: A Comprehensive Guide to the Peloponnesian War, Free Press, 1996, page 352-354