My current project is a study of the uses to which the Nazis put the astonishing forgery The Protocols of the Elders of Zion. That document purports to be the records of a secret Jewish conclave that discussed progress in the Jewish campaign to take absolute world power. It is popular today in the Arab world (Egyptian television apparently did a series based on it), but even in the United States there are adherents. Look over the discussion page for the Wikipedia article on the Protocols if you are curious to see some of its believers struggling to defend its authenticity.
The Protocols were first published in German shortly after the end of World War I. There were a variety of editions, but the most successful was that by Gottfried zur Beek (a pseudonym for Ludwig Müller von Hausen). It was taken over by the Nazi Party’s publishing house and had at least 22 printings. I have not been able to determine the number of copies printed, but it has to have been in the millions.
The 1938 edition shown above included a lengthy introduction that attempted to prove its genuineness that I add to the GPA today. It makes remarkable reading. The author (whose name is not given) follows the usual methods of such conspiratorial nonsense — providing a wide variety of “evidence” that does not hang together in a way that supports the case.