The History of the Grecian War (1.87.2-1.87.4)

and saying afterwards that he could not discern whether was the greater cry (for they used there to give their votes viva voce and not with balls) and desiring that it might be evident that their minds were inclined most to the war, he put it unto them again and said, to whomsoever of you it seemeth that the peace is broken and that the Athenians have done unjustly, let him arise and go yonder, and withal he showed them a certain place, and to whomsoever it seemeth otherwise, let him go to the other side.

So they arose and the room was divided, wherein far the greater number were those that held the peace to be broken.

Then calling in the confederates they told them that for their own parts their sentence was that the Athenians had done them wrong; but yet they desired to have all their confederates called together, and then to put it to the question again that if they would, the war might be decreed by common consent.