The peace sign looks something like this yes?: \\\\// ||
Well when the french and british were fighting in medieval times, the french archers used to put their fingers up in the "Up Yours" sign and then with the same sign, drew their bow and fired. This was meant as an insult.
The peace sign was made because it is physically impossible to draw a bow using the knuckle side of your fingers. It is strange though how you use the drawing side of your fingers to show the peace sign and you use the knuckle side of your fingers to say up yours even though you cannot draw a bow with them.