Where Did The Happy Birthday Song Originally Come From?

You know that song that goes:

Da Da Da Da doo doo
Da Da Da Da doo doo
Da Da Daaa Da doo doo dooooo
Da Da Da Da doo doo......

Where did that come from? Was that an old army song from back in the Cival War? Maybe they sang that right before they went into battle as a way of saying, "Gee, I hope we get to see our next birthday...I hope we don't get hit by a cannon ball or something...." You think?

When was the first time someone actually sang that song to someone else? Was it on their actual birthday? Or was it a few days before or after their actual birthday?

I can't seem to find any info on that.