Regarding colour-coded uniforms. I have been told that the move from bright colours to camouflage took place during the Boer Wars in South Africa. And that it happened because the nature of warfare changed. If the battle consists of two armies standing against each other on a big field and fighting with swords in an almighty mishmash, it helps if you can tell friend from foe instantly. Once you can kill each other from a distance, you can tell who is on your side just by means of proximity and bright colours become a disadvantage.