History of the Peloponnesian War

Theramenes also, the son of Hagnon, was foremost among those who attempted to overthrow the democracy, being a man of no small capacity either in speech or in judgment. Consequently, conducted as it was by many able men, the plot not unnaturally succeeded, even though it was an arduous task; for it was difficult, after the lapse of almost one hundred years[*](Really 99 years: from 510 to 411.) since the tyrants had been overthrown, to deprive of their liberty the Athenian people, who had been, not only not subject to anyone else, but for more than half of that period had themselves been accustomed to rule over others.

When the assembly had been dissolved, with no opposition from anyone and immediately after sanctioning these measures, the leaders of the oligarchy then introduced the Four Hundred into the senate-chamber in the following manner: all the Athenians were at all times under arms, as a precaution against the enemy at Deceleia, some on the walls and some in the ranks.

On that day, then, they let those who were not privy to their design go away as usual, but those who were in the conspiracy had been quietly told to remain, not close by their arms, but at some distance from them, and if anybody tried to oppose what was going on, to take their arms and permit no interference.