A Confederate enlisted man’s shell jacket made of grayish brown wool. This coarse and simple uniform became widely used by Confederate troops, particularly the Western Theater. The uniform was originally gray in appearance but turned a "butternut brown" when exposed to the sun. The dye used in these inexpensive wool and cotton blend uniforms often came from butternuts, walnut shells, and rust. Their earth-tone color is what caused the Federals to sometimes call Rebels "Butternuts."