I agree on the difference between picking a fight & defending yourself.
When my brother was little, he came home one day from school crying, my mom asked him what was up & he said that a girl beat him up. My mom asked him what he did & my brother said "nothing, I can't hit a girl" so my mother proceeded to ask him who told him that!! She went on to tell him that picking a fight & hitting a girl is wrong but she never told him that defending himself, be it a girl or a boy was wrong. He was pretty happy to hear that.
I teach my kids that hitting in anger is wrong, but hey, if someone is pummeling them, I don't expect them to sit there & take it. I've only got experience from having little brothers & fights, and while my mom took concern with any injuries (they were usually minimal) she found it best to stay out of kid squabbles. They never escalated past a hit here & there and usually they kids would be friends again the next day. OF course that's different these days isn't it? Hopefully when my son is in school and goes thru this, I'll be able to take the same path & step in only if it's absolutely necessary, and then deal with the problem first hand!
SK