It began with WWI, beards hindered gas mask sealing. That led to the rise in clean shaven being seen as professional as well as the origin of the postage stamp mustache (as made memorable by a certain Austrian and an actor who hated him)

America loved beards in the 19th century and mustaches were in in the early 20th. Facial hair trends come and go, we were into clean shaven looks in the 18th century, and even wore the stupid wigs the brits liked then.