Epaulettes began as ribbons to stop belts sliding off soldiers' shoulders
The gold-fringed shoulder pieces on dress uniforms started life as a practical fix. In the late 17th century, soldiers tied bunches of ribbon on their coat shoulders, partly for show and partly to keep shoulder belts in place. The knotted, fringed ribbon became the template for a badge of rank.
The word is French for little shoulder, a diminutive of epaule. An epaulette is fixed either by a small strap running parallel to the shoulder seam plus a button near the collar, or by laces threaded through holes in the coat. Rank is read from where it sits, its colour and the length and thickness of its bullion fringe, and a crescent-shaped metal piece often joins fringe to shoulder. Once worn in the field, epaulettes now mostly appear only on dress and ceremonial uniforms.
They loosely recall the shoulder pteruges of ancient Greek and Roman armour, but their real ancestor is that ribbon knot, refined through the 18th and 19th centuries. By the early 18th century they marked commissioned officers so clearly that officers in units without them petitioned to wear them. The French and other armies used placement to show rank: left shoulder, right shoulder or both, with an unfringed counter-epaulette on the bare side. Officers wore silver or gold; enlisted men had coloured cloth according to their branch.
During the Napoleonic Wars and afterwards, grenadiers, light infantry, voltigeurs and other specialists wore wool-fringed cloth epaulettes to stand apart from line infantry, and heavy artillery sported little balls representing ammunition. Flexible brass versions, called shoulder scales, were issued to the US Cavalry, Infantry and Artillery from 1854 to 1872, though rarely used in combat.
Simplification followed. Armies such as Russia's adopted the fringeless shoulder board for everyday service, and a five-sided cloth flap buttoned at the end has largely replaced the epaulette. From it came the shoulder mark, a cloth sleeve slipped over a strap so insignia can be swapped easily. Airline pilots wear a version with stripes, traditionally four for a captain, though each airline sets its own scheme.
Source: Epaulette