The standard of clean shaving started in the 1920s, following the return of USAan doughboys from France. Prior to that period, most men had beards or mustaches, or sideburns (named for Ambrose Burnsides, federal Civil War general, whose sideburns were phenomenal). But the Roman army was clean shaven because a beard gave the enemy a handhold he could exploit: grab and pull. The invention of gunpowder and firearms made shaving unnecessary, so for the next three or four centuries beards were a