Before the Twentieth Century epaulettes and shoulder straps were common devices to signal rank. Epaulettes, from epaule an old French word for shoulder, seem to have started out as cloth straps worn on the shoulders to help keep shoulder sashes and belts in position. Another story has them beginning as pieces of armor to protect the shoulders. By the time of our Revolutionary War epaulettes worn by British and French officers had become elaborate affairs of gold or silver that started at the collar and ended at the point of the shoulder with heavy fringes of gold or silver wire. To some they looked like fancy hair brushes. They were also very expensive being made of gold or silver, sometimes solid metal and other times plated. Epaulettes for Sergeants and other enlisted men were of cheaper metals or cloth. In our Army officers started wearing gold or silver epaulettes in 1780 during the Revolutionary War and continued to do so until 1872, mostly on their dress uniforms. Army general wore epaulettes until early in the Twentieth Century. Navy officers also started wearing epaulettes during the Revolutionary War and did not give them up for their full dress uniforms until just before World War II. Marine officers wore epaulettes on their special full dress uniforms until 1922.
The embroidered rank insignia usually appeared on the epaulette strap or near the "crescent," the rounded portion over the end of the shoulder. For some ranks, such as Major or Second Lieutenant, the size of these were the epaulette or the size of the fringes were the main clues of rank since those officers did not wear insignia.
Along with being expensive, epaulettes made pretty good targets so the Army switched to shoulder straps in 1831 for other than dress uniforms. The Navy had been using straps since 1830. The officers wore the straps across their shoulders at the sleeve seams of their coats. Usually the straps had raised edges of embroidered gold or silver with the rank insignia embroidered between the edges. Navy officers wore shoulder straps until 1899 when they changed to their current shoulder marks. Army and Marine officers wore the straps until the first few years of this century when they changed to metal pin-on type insignia. They started wearing the metal insignia just before the end of the Nineteenth Century on their new khaki or olive drab uniforms but also wore the straps on some uniforms. Army officers still wear shoulder straps on their blue uniforms. Many also wear embroidered insignia.
Navy officers started wearing stripes of gold lace on their sleeve cuffs in 1852 but in different patterns than today. Captains, for instance, had just three stripes. I will tell when each rank got its current number of stripes when I discuss that rank. The use of metal pin-on rank insignia by Navy officers started in 1941 when they wore the insignia on the collars of their khaki shirts.