Interesting question...
Here are some thoughts from the interweb...
https://en.wikipedia.org/wiki/Moustache
"Moustache popularity in the 19th century peaked in the 1880s and 1890s coinciding with a popularity in the military virtues of the day."
From this reference article:
http://blog.wellcomelibrary.org/2015...ary-moustache/
And there was this neat graph (although I have no idea how accurate it is...) from this GQ article:
https://www.gq.com/story/facial-hair-trends-over-time