Here are some precedents you may find interesting:
In the 12th century, legends began to promulgate throughout Christian Europe of a figure named "Prestor John", rumored to be the ruler of a rich and powerful kingdom in "the East" (at first, legend places him somewhere in India -- specifically the Three Indies -- but over time, his location would shift to various other favored exotic places which reappear in the Medieval imagination, such as Ethiopia).
Around 1165, a forged letter began to circulate Europe, purportedly from Prestor John himself. The crux of the letter centered around the fact that a remnant Nestorian Christian kingdom was holding out in the East, at the head of which was this Prestor John, and that he wished to vanquish the enemies of Christ. This was VERY popular in Europe at the time, the more recent Crusades not having gone well, and the letter with its surrounding legend "went viral" over the continent. Pope Alexander III attempted to make contact. Marco Polo discusses him in depth.
In 1862, Mark Twain fabricated a story wherein he claimed a petrified man had been discovered preserved in the side of a cliff. The story caused a sensation, and the small town where this petrified man was supposedly located was flooded with inquiries. Twain had reported in great detail the exact positions of limbs:
“the right thumb rested against the side of the nose; the left thumb partially supported the chin, the fore-finger pressed the inner corner of the left eye, drawing it partly open; the right eye was closed, and the fingers of the right hand spread apart.”
A careful reading would have revealed that this unearthed man was literally "thumbing his nose" at his credulous readers.
Mark Twain was a bit of a "troll" in his day: he would also fabricate the story of the Empire City Massacre, wherein a man, losing everything in a bad investment, committed a murder/suicide on his wife and seven children. Twain wrote the piece in protest of contemporary bad business practices.
In June, 1899, newspapers across the US ran a story about American businessmen vying with one another for the right to tear down the Great Wall of China for the purpose of using its stone to build roads. However, this turned out to be a hoax, perpetrated by four Denver newspapermen who had deadlines due and no stories to fill them. The story caught on, and in days even the New York Times succumbed to the hoax, running this headline: "WILL CHINA'S WALL COME DOWN?" As various newspapers across the country picked up the story, the occasional embellishment would find its way in. In the end, this hoax would spawn a daughter-hoax: that of news of the Great Wall Hoax made its way to China and wound up being responsible for a popular uprising that would be known as the Boxer Rebellion.
Is it even true that the entire nation was hoaxed? Wasn't the panic itself exaggerated by the press?
An early and enormous example is the bat men of the moon hoax perpetrated by the New York Sun in August 1835. In a series of six articles written by Richard Locke, the New York Sun saw a dramatic increase in its circulation. These articles decribed a large telescope, which used a new scientific principal. It also described the large cities and curious bat men that lived on the moon. The intention was not to frighten the people of New York with an imminent attack from the moon. More than half of the readers of the New York Sun did not believe the story anyway. After just six instalments of this series, the New York Sun revealed it was a hoax, yet it continued to maintain its increased circulation.
Source: "The Sun and the Moon: The Remarkable Account of Hoaxers, Showmen, Dueling Journalists and Lunar Man-bats in Nineteenth Century New York City." by Matthew Goodman (2008)
Add to these the Piltdown man, the fake pre-historic man found in England (it was carved stone), the fake diaries of Adolf Hitler and the fake biography of Howard Hughes--all of which were believed by a fairly large number of people.