When I was growing up, my Dad, (a proper English Gentleman who emigrated in the 50's) was the soul of courtesy, a good example.
However when he saw something that was obviously rude and uncalled for, especially to a female, he would take all 6'2" of his polite English self and be shockingly direct, without raising his voice but with a very steady look on his face. No one ever saw fit to make an issue of it.
This is a man who as a child during WWII on the outskirts of London slept under what amounted to a large table built out of oak 4x4 timbers. The theory being that if the house were hit by bombs the "bomb shelter" would leave you in an air pocket and you could be dug out (hopefully) alive. It changed him. He hates Bullies, and taught me to confront them in turn.
Every day I am armed, in large part due to the good advice I've gotten here (thanks Frank), I have to remind myself not to follow his example.
Sad, really.