(Read it here)
Published anonymously (due to its treasonous content) on January 10th, 1776, Thomas Paine's 43-page pamphlet, Common Sense, became one of the foundational documents of the early American Republic, and of the modern American mind as well.
Paine said in a later treatise that "the moral principle of revolutions is to instruct, not to destroy." And instruct he did, in a long series of works that influenced both the American and French Revolutions. But he never did it better than with his first pamphlet. You may judge how much influence Common Sense had on contemporary events by the fact that it sold 500,000 copies during 1776 alone, when there were only 2.5 million people living in all 13 colonies.
Has any other piece of propaganda [and I use that word non-pejoratively, since I think it's more forthright than the rather euphemistic P-word synonyms that replaced it, e.g., psychological operations, political warfare, perception management, or even public diplomacy] since 1776 been remotely as successful?