During the battle of Agincort a number of British archers were captured by the French. They were eventually returned, with the first two digits of their right hands removed, preventing them from firing a bow again. Displaying those digits became an insult originally aimed at the French that broadly made its way to general use
viriosion t1_iydspfo wrote
Reply to comment by HollyCupcakez in A middle finger is half way to a peace sign by billychasen
For some (anecdotal) historical context
During the battle of Agincort a number of British archers were captured by the French. They were eventually returned, with the first two digits of their right hands removed, preventing them from firing a bow again. Displaying those digits became an insult originally aimed at the French that broadly made its way to general use