Slang can rarely be traced with any certainty, and the word “camouflage”, prior to World War I, was Parisian slang.
It was the smoke blown into a person’s eyes, in fun or seriously, to blind him from observing what was going on around him. Thus, in reverse, it was a kind of smoke screen.
And, in World War I, it may have been that the term was first applied to a smoke screen, a screen of smoke emitted by a vessel to conceal its movements from an enemy or to make difficult the determination of the distance between them.
But it was found that a ship painted in varicolored designs was likely to escape detection entirely, and thus camouflage came to embrace any kind of disguise.
It is probable that the word came from an earlier French military term, camouflet.
This was applied to a kind of bomb which was discharged, by countermining, within the mine of an enemy.
It was filled with a powder which, when discharged, would emit dense fumes that would asphyxiate the enemy’s mine crew.