Philip Freeman, a classics professor at Luther College, is the editor of “How to Win an Election: An Ancient Guide for Modern Politicians.”

A.D. 79 was a rough year for Marcus Cerrinius Vatia. The up-and-coming young man was running for the important office of aedile, one of the two junior magistrates in the seaside town of Pompeii. A century earlier, the Roman orator Cicero had admired the generally honest and upright campaigns conducted in this provincial town on the Bay of Naples. Unlike in Rome itself, where corruption was rampant, any hardworking Pompeian man with enough money and friends might rise to the office of aedile — unless he was a member of an undesirable profession, a public executioner, for example, or an actor....

But politics could be a dirty business, even in Pompeii. Sometime in the night, one of the professional political teams that painted signs around town whitewashed some old campaign ads from the previous year and replaced them with new graffiti, including “The petty thieves support Vatia for aedile” and “The late night drinkers all ask you to elect Marcus Cerrinius Vatia as aedile.” Poor Vatia had become a victim of negative campaign advertising....