That would be "Snoopy Vs. The Red Baron" by the Royal Guardsmen from 1967. It was a big chart hit as well. I haven't heard that song on the radio in quite a while but I have it on a couple of compilations.
Nope. "Snoopy's Christmas" (Christmas bells, those Christmas bells, ringing through the land, bringing peace to all the world, and good will to man) was a sequel to "Snoopy and the Red Baron" (Ten, twenty, thirty, forty, fifty or more, the bloody Red Baron was rolling up the score... eighty men died trying to end that spree, of the bloody Red Baron of Germany), also done by the Royal Guardmen, the lead singer of whom later transmogrified himself into 'Lobo' ("Me 'n You and a Dog Named Boo", and "I Love You Too Much to Ever Start Liking You").
Whether or not this was an improvement is still bitterly debated in pop circles.
That to the side, "Snoopy's Christmas" is relatively innocuous, and should be removed from the Christmas Song Death List...
(As a parenthetical aside, it concerns me somewhat that I know this stuff off the top of my head.)
Wow. I thought I knew a lot of useless crap. I bow down to the master.