When did John Lennon and Yoko Ono make the song Happy Christmas War is Over?

John Lennon and Yoko Ono wrote the song (whose first line is "And so this is Christmas", so it is sometimes mistaken for the title) in their New York City hotel room, and recorded it (with the Harlem Community Boys Choir) during the evening of October 28 and into the morning of the 29th, 1971 at the Record Plant in New York. It was released in the US for Christmas, but didn't chart. The next year, it was released in the UK, where it did much better.