How did Thucydides portray the fate of Plataea during the Peloponnesian War?

In his historical account, Thucydides portrays the fate of Plataea as a tragic illustration of the cruelty and political instability that defined the Peloponnesian War.1

Through his narrative and the use of speeches, Thucydides highlights the city's harsh end, which he attributes to the long-standing, embittered envy of Thebes and the ultimate faithlessness of Sparta. When the remaining Plataeans surrendered in 427 BCE, they were subjected to a brief, cynical interrogation by the Spartans: "Have you done anything for Sparta during the war?" Despite their moving pleas, the Plataeans could only answer negatively, leading the Spartans to execute the men to a man.12

Thucydides uses this episode to reflect on the broader moral decay of the era, linking the brutality faced by the Plataeans to the general "corrosion of the human spirit" caused by the prolonged conflict. By documenting these events, he provides a stark critique of the strategic coldness and lack of mercy that characterized the actions of the major powers during the war.12