In the late 1700’s, British soldiers adopted the French requirement to have facial hair styled in a way that reflected their station and the type of soldier they were. For example, "sappers" were required to wear a full beard; "grenadiers" wore bushy, large moustaches. Infantry wore a goatee to keep their moustache company. Facial hair was seen as a symbol of aggression and virility; in India and Arab nations, a bare face was perceived as being weak and juvenile. For a long time, British soldiers rejected the notion, but in time they too adopted it.
In 1854, the East India Company’s Bombay Army made the moustache a compulsory feature for its troops. It was also adopted by soldiers fighting in the Crimean War, and many opulent moustache styles were worn.
Between 1860 and 1916, British Army uniform regulations stipulated very clearly that each and every soldier should wear a moustache. According to regulations, a soldier must keep the hair on his head short and trimmed neatly; he must shave the chin and under the lower lip, but must not shave the upper lip. To shave the upper lip was considered to be breaching discipline, and one could even be imprisoned for what seems like a trivial concern.
It wasn’t until 1916 and World War I that the regulation was dropped; many men again became clean shaven, and in part this was because moustaches impeded the seal on the gas masks which soldiers of the time were required to wear. Perhaps if they had a Milkman Mo Stick, they could keep those hairs in check.
Even today, there are regulations in the army regarding the wearing of a moustache. It must not extend beyond the upper lip. Members of the French Foreign Legion are expected to wear a full beard. British soldiers, particularly those fighting in Islamic nations where facial hair remains a symbol of power and authority, often still choose to grow a mo.