Opposition research is as old as politics itself—Cicero's orations against Catiline, a dodgy candidate for the Roman consulship in 63BC, were notably well-informed.
You also had statesmen like Pericles, whose famous funeral oration brags about the golden democracy of Athens with rhetoric that wouldn’t sound out of place today.
At Pueblo, Colorado, he stumbled while stepping up to the speaker's platform, but he went on to deliver an emotional oration that brought tears to many eyes.