The version of this most foul gesture that Hairbear recounts varies, but is commonly believed by most folklorists to be false. The origins of the story are reputed to have been started by Shakespeare’s graphic description of the 1415 battle of Agincourt in his "Henry V." The story recounts that British troops chided their French enemies with the gesture. It would not surprise me at all to learn that this variant of the popular "fuck you" gesture gained its popularity and wide spread use from Shakespeare’s influence, rather than from the battle it was supposedly used in.
Which isn't to say that Shakespeare created the rather universal gesture of "The bird." Indeed many scholars, including author of the book "The F Word" Jesse Sheidlower account that the gesture "Goes back a hell of a long way. About 2,000 years or so. To ancient Rome." those denizens of marble halls called it the digitus Impudicus which meant the "dirty finger" or "the impudent finger."
According to Reinhold Aman, the publisher of "Maledicta: The International Journal of Verbal Aggression," the gesture was meant to symbolize the act of anal intercourse and was used as a degrading threat against another person.
The gesture itself is universal. You may have never seen it, but humans are such close studies of body language that the meaning is well understood. The quick upwards thrust of the hand with both fingers being jammed threateningly skyward, is often accompanied by some verbal assault and facial expression of ire that would be clear even to a child that didn't speak the language.
It's of import to note that the "V" gesture is only considered vulgar when the knuckles face the victim and the palm faces the user. If you turn it around and face the palm towards the victim, the meaning of the gesture is changed dramatically to one of victory, peace, and corporate pandering on nostalgia.