Yellow Submarine is a soundtrack album released by The Beatles corresponding with the film of the same name released on Apple Records during January 1969

"Only a Northern Song" was originally recorded during the sessions for the Sgt. Pepper's Lonely Hearts Club Band album, although it did not appear there. Most of the song was recorded in February 1967. "It's All Too Much" was recorded just before the release of Sgt. Pepper, although it was shortened (from eight minutes) for Yellow Submarine. "Hey Bulldog" (recorded in February 1968) and "All Together Now" (recorded in May 1967) were always intended for the film soundtrack. "Baby You're a Rich Man" was also originally intended for the film soundtrack, but was released as the B-side to "All You Need is Love" instead and was not included in the Yellow Submarine album.

Two of the songs on the album had previously been released. "Yellow Submarine" had already appeared on Revolver in August 1966 and as a hit single at about the same time. "All You Need Is Love" had been a hit single in 1967 and had also appeared in the United States edition of Magical Mystery Tour later that year. The song made its true stereo debut in this album. The song was previously issued in mono or rechanneled stereo on the U.S. Magical Mystery Tour album. The second side features arrangements (recorded specifically for the album) of George Martin's orchestral score.

After mixed response to the album upon its release, The Beatles considered releasing Yellow Submarine as a five-track mono EP, without the film score but including the then-unreleased "Across the Universe" as a bonus track. The EP was mastered, but never issued. wikipedia