I remember being taught that using the two fingered 'V-sign' as an insulting gesture had its origins back in the wars between England and France.
The Weapon of Mass Destruction of the day was the longbow, and all able-bodied Englishmen were required by law to practise using one at least once a week in peace-time.
English archers taken prisoner by the French suffered the amputation of the index and second fingers from the hand they drew the bow with to prevent them from ever being able to use one again.
Hence Englishmen who had never been captured would use the V-sign to taunt their French opposition and show they were able to draw and fire the longbow.