existing banknotes, in response to a fraud perpetrated by Alves dos Reis. Similarly, in 1929 the issue of postage stamps celebrating the Millennium of Iceland's parliament, the Althing, was compromised by the insertion of "1" on the print order, before the authorised value of stamps to be produced (see Postage stamps and postal history of Iceland.)
In 1926 a high-profile counterfeit scandal came to light in Hungary, when several people were arrested in the Netherlands while attempting to procure 10 million francs worth of fake French 1000-franc bills which had been produced in Hungary; after 3 years, the state-sponsored industrial scale counterfeit operation had finally collapsed. The League of Nations' investigation found Hungary's motives were to avenge its post-WWI territorial losses (blamed on Georges Clemenceau) and to use profits from the counterfeiting business to boost a militarist, border-revisionist ideology. Germany and Austria had an active role in the conspiracy, which required special machinery. The quality of fake bills was still substandard however, due to France's use of exotic raw paper material imported from its colonies.
During World War II, the Nazis attempted to do a similar thing to the Allies with Operation Bernhard. The Nazis took Jewish artists in the Sachsenhausen concentration camp and forced them to forge British pounds and American dollars. The quality of the counterfeiting was very good, and it was almost impossible to distinguish between the real and fake bills. The Germans could not put their plan into action, and were forced to dump the counterfeit bills into a lake. The bills were not recovered until the 1950s.