The origins of the 'V-sign', as a gesture of contempt
supposedly go back several hundred years to the time of the Hundred Years War
in the 14th and 15th centuries.
English Archers were the most feared in the world. Armed with a longbow capable of punching an arrow through the armour of a French mounted knight at huge distances, they were the mainstay of many of the English armies at the time, as they could cut down swathes of enemy soldiers from a range at which they couldn't be matched by the French archers.
Due to their devastating ability, captured English archers had the first two fingers of their right hand cut off, so that they could no longer draw a bow, no longer posed a threat to the French. This lead to the practice of uncaptured archers taunting the French after felling one of their number with an arrow, by raising his two fingers, to show he was still in the game.