I was wondering… reading elsewhere online about terms and confusion regarding "double actions". Are they double actions because pulling the trigger cause two actions, cocking and firing? Or are they double actions because they can be fired two ways, cocked manually and fired, or just by pulling the trigger. (don't let the latter "double action only" cloud your choice.

BUT THAT ISN'T MY QUESTION. Question is...

When did single action revolvers start being called "single action?"
When did the "Single Action Army" become named such?
I would assume it was after someone invented the "double action", no?
If not, the why would you call it that?

Ideas, input, historical fact???