How did it originate?

https://www.history.com/news/how-did-taps-originate

https://en.wikipedia.org/wiki/Taps

https://www.youtube.com/watch?v=KKhhg2CqcCQ

Notice the Comment following "Day Is Done" from a person named Robert Lombardo (2 years ago)

"I was never a soldier. But I'm going through some real... REAL hard times in life recently. When I'm all alone at night and feel isolated I play this and try to imagine that all is well, the sentries are posted, and it's safe for me to go to sleep because God is here with me."

I hope Mr. Lombardo is doing well.

With you on that Ken.
I got to where I could hit most of the notes on my beat-up Boy Scout bugle, but the most reverent rendering was when we would just sing it quietly around the campfire before going to our tents.
It is especially moving when the notes are heard floating in the sacred air of a national cemetery.