Hi Andy
The breach refers to the city walls of Harfleur (battle of Agincourt)
The two fingered salute at Agincourt being linked to fingers being cut off is something of a myth and there are a lot of reasons to doubt its veracity. According to anthropologists, hostile gestures involving jerking movements of parts of the hand or forearm are found in many, if not most, cultures.
There's no record of captured bowmen being mutilated at Agincourt, or elsewhere; if the practice had been widespread enough to launch the V-sign, such records would surely exist, from a time when all
aspects of warfare were closely scrutinised and chronicled.
Paul