Functional Features of Military Uniforms

Way back when, between wars, a French officer and a British officer were amiably discussing tactics and other military matters.  The French officer, rather disdainfully asked the British officer why they wore bright red coats into battle.  "It brings attention to you as if to say, look at me, I am a target".  The Brit replied, " it's so that if I am wounded, the blood will not be so obvious and my men will not worry".  "By the way old chap, why do French officers wear dark brown trousers"?