Military moustaches came out of the British Army getting teased
During the process of colonization, British men were teased by Indian men, who had glorious moustaches. Told they looked like children, the British officers begged their commanders for permission to grow at least a lip broom.
So, by the 1860’s, moustaches became compulsory in the British Army. This rule was dropped in 1916, when they got in the way of gas masks.