History of the Peloponnesian War

Theramenes the son of Hagnon was also a leader amongst those who joined in abolishing the democracy, a man of no small power, either of language or intellect. So that, conducted as it was by so many clever men, it was not unnatural that the business should succeed, though an arduous one. For it was a difficult matter to deprive the Athenian people of its liberty, about a hundred years after the deposition of the tyrants, and when it had not only been subject to none, but accustomed also, for more than half of that period, to rule over others.

When the assembly had been dissolved, without contradiction from any one, and by its own ratificaion of the measure, then they afterwards introduced the Four Hundred into the council-chamber, in the following manner. All the Athenians, in consequence of the enemy established at Decelea, were constantly under arms, either on the walls or in the ranks.