The Origin of Douglas.
To my knowledge there is no hard evidence of Douglas' Origin.
There are two theories that I know of.
Some people think, talk and write about one of these, some the other,
One theory is that he was one of, or the descendant of, One of Jefferson Davis Camel Corps which was located in West Texas, New Mexico, Arizona and perhaps Southern California,
The other theory was that he was imported for a farm animal on one of the plantations in the Columbus, Mississippi, area or neighboring Alabama.
I would think one of these theories is correct, however, i have no idea which one is correct.