Thucydides on the outbreak of the Archidamian war

The Peloponnesian War started with a covert operation. It was important for Thebes to capture Plataea, because it controlled the roads to the Theban allies on the Peloponnese (Corinth and Sparta), and it is not surprising that the Thebans wanted to capture the town. They preferred to take Plataea by treason: a traitor let them in during the rainy night of c. 6 March 431. It was a complete violation of the code of honor that had once ruled Greek warfare, but, as Thucydides pointed out in a different context, "The ancient simplicity was laughed down and disappeared".^note

During the night, the traitors discovered that the Thebans, who were supposed to kill many Plataeans, had completely different designs. As could be expected, those Plataeans who had been surprised by the conspiracy fought back, and in the end captured the Theban attackers. They were almost immediately killed. Violation of a peace treaty, treason, double-crossing, killing POWs: the attack on Plataea was a worthy prologue to the war.

The translation of History of the Peloponnesian War 2.2.1-6.3 was made by Richard Crawley.

Book

Chapter

Section

Thucydides on the outbreak of the Archidamian war
[2.2.1] The Thirty Years' truce,^note which was entered into after the conquest of Euboea, lasted fourteen years. In the fifteenth, in the forty-eighth year of the priestessship of Chrysis at Argos, in the ephorate of Aenesias at Sparta, in the last month but two of the archonship of Pythodorus at Athens, and six months after the battle of Potidaea, just at the beginning of spring, a Theban force a little over 300 strong, under the command of their Boeotarchs, Pythangelus, son of Phyleides, and Diemporus, son of Onetorides, about the first watch of the night, made an armed entry into Plataea, a town of Boeotia in alliance with Athens.
[2.2.2] The gates were opened to them by a Plataean called Naucleides, who, with his party, had invited them in, meaning to put to death the citizens of the opposite party, bring over the city to Thebes, and thus obtain power for themselves.
[2.2.3] This was arranged through Eurymachus, son of Leontiades, a person of great influence at Thebes. Plataea had always been at variance with Thebes; and the latter, foreseeing that war was at hand, wished to surprise her old enemy in time of peace, before hostilities had actually broken out. Indeed this was how they got in so easily without being observed, as no guard had been posted.
[2.2.4] After the soldiers had grounded arms in the market-place, those who had invited them in wished them to set to work at once and go to their enemies' houses. This, however, the Thebans refused to do, but determined to make a conciliatory proclamation, and if possible to come to a friendly understanding with the citizens. Their herald accordingly invited any who wished to resume their old place in the confederacy of their countrymen^note to ground arms with them, for they thought that in this way the city would readily join them.