See, nobody could ever know whether their side of the story is the truth or otherwise. I see that the light of this discussion is not much on Mel Gibson, but indeed on the movie and most of all, your pride as a British. I know that this rivalry feeling is something you couldn't escape for being a British, but let the emotional feelings go. I think, the British side must also take the responsibility for invading America, for which the action was readily a cruel and brutal act from the beginning. Never mind the historical facts, for they could be as fake as the movie as well.
Nobody ever knows.
So, I think it is a bit unfair for you to condemn Mel for all these because it is just a movie. Furthermore, I don't think anybody believe anything from Hollywood. Thus, just leave him alone. He is a good actor and director, who shouldn't be messed up with small matters like your hurting pride. Many of your points are already covered in other correspondence.