The operation had not gone as planned. A strike force of some 300 Thebans had gained entrance to the walled city of Plataea under cover of darkness. The gates lay open, no guards had challenged them, and they soon occupied a strong position in the agora. They held the advantage of complete surprise. But soon they were desperately trying to find their way out again, for the Plataeans had blocked the narrow lanes with wagons and barricaded the gates. Hampered by rain and darkness and lost in a maze of unfamiliar streets, the Thebans came under attack from all sides and were pelted from above with stones and roof tiles. They fled as they could, with pursuers at their heels. Those who reached the outer wall hurled themselves over to break or die on the ground below. Others fought desperately in corners and alleyways. By the time dawn broke, all who remained inside had been slain or taken captive.
Decades before the 431 BC attack on Plataea a once united Greece had divided into hostile camps, and war had broken out. Ironically, Plataea had been the site of a decisive victory of allied Panhellenic forces over invading Persians in 479 BC. But in the half century since much had changed. The cobbled unity occasioned by the Greco-Persian War had eroded as the growing hegemony of Athens, founder and dominant member of the Delian League of city-states, created unease and mistrust among members of the Peloponnesian League, dominated by Sparta. During the resulting 460–45 BC war the rivals circled each other like boxers, engaging in proxy fights through allies as they measured one another’s strength. Signed in 446–45 BC, the Thirty
