Where is this phrase from- "barring fire, flood, or civil unrest?" [edited title]

What is the origin of the phrase “barring fire, flood, or civil unrest?”
I have searched a number of etymology sites, and asked at grammarphobia.com. I have asked our local reference librarian. No one can identify it. My sense is that it might be a clause from some form of old contract, but I invented that idea. I can Google it and find lots of other usage examples, but so far none has pointed to its origin. The person I heard it from would now be 90, and lived in NE Pa. His father was a stockbroker and attended an Ivy-league university in the nineteen-teens (pre WWI.)

If you make a more informative subject header you might get more responses.

Ask a mod.

I’ve done this for him just now.

Sounds like a way of saying “Come Hell or high water” to me, and I think you are right in thinking it has to do with contracts - those things are covered by “Force Majeure”.