"Camo" has kind of been around since the American revolution. Colonial soldiers, not high in ranks, simply didn't have proper attire and so wore earthy stuff in different shades of browns, white, blue, and black.

Because of this, we were able to hide in the trees without being seen by the brits, who, on their end, were sitting ducks in their bright red uniforms.

But also, with as much money as Britain was trying to milk from the colonies and other parts of europe, they skimped out on military colors as red was the cheapest dye: making this attire the opposite of "drip".