-- Ben Franklin, http://en.wikiquote.org/wiki/Benjamin_Franklin
"Oceania has always been at war with Eastasia"
-- Ministry of Truth radio address, in George Orwell's novel 1984 : http://en.wikipedia.org/wiki/Nineteen_Eighty-Four. As noted in the WP article, the announcer changes the name of the eternal enemy halfway through an address.
I'm a bit behind on my Escape Pod, but this one seems to be on the same topic: http://escapepod.org/2007/08/23/ep120-the-sundial-brigade/