The earliest known recording of "Give Peace a Chance" is one of the many extras that are on the John Lennon/Plastic Ono Band– The Ultimate Collection, which is out on April 23rd.
The audio is taken from a film of John rehearsing the song at the Sheraton Oceanus Hotel in the Bahamas on May 25th, 1969.
The film features John humorously adlibbing lyrics for the verses before being joined by Yoko for the chorus that became an anti-war anthem and remains an enduring protest song more than 50 years later.