"The big lie"
The phrase was also used in a report prepared during the war by the United States Office of Strategic Services in describing Hitler's psychological profile.
His primary rules were: never allow the public to cool off; never admit a fault or wrong; never concede that there may be some good in your enemy; never leave room for alternatives; never accept blame; concentrate on one enemy at a time and blame him for everything that goes wrong; people will believe a big lie sooner than a little one; and if you repeat it frequently enough people will sooner or later believe it.
From here.
http://en.wikipedia.org/wiki/Big_Lie