The idea of color-coding uniforms has been around for more than 2,000 years. The Carthaginian general Hannibal, well-known for trekking elephants across the Alps in his battle against the Romans, is credited with developing the idea in the 3rd century B.C.
By dressing his soldiers in a white tunic with a crimson edge, he was able to see at a glance who was part of his army and who was not. It was an ingenious, practical idea that has since found many uses.