In 1809, Captain Meriwether Lewis rested at the "Grinder's Stand", an inn on the Natchez Trace, seventy miles south-west of Nashville, Tennessee.
Meriwether Lewis Defeats Muggers, Redux By Ed, Scott Palter and Jeff ProvineAfter leaving dinner, he retired only to be savagely attacked in his bedroom. He managed to drive off the unidentified muggers, but immediately discovered that they had made off with the journals that he was carrying to Washington, D.C. for publication.
Of course not long after his death in 1846, the "secret journals of Capt. Lewis" appeared. This narrative of the Lewis and Clark Expedition described the Corps of Discovery finding giants, the fountain of youth, and a tribe of "nearly white, blue-eyed" Indians descended from Prince Madoc of Wales.
Clearly at odds with the known facts, this account was of course a naked challenge to westward expansion. Conspiracy theorists suggested that the muggers were agents sent by the Federal Government to cover-up the truth of advanced indigenous civilization predating Columbus, but mainstream historians  suggested that too many people had traveled westward with Lewis and Clark for such revelations to be concealed.