There is an interesting post about the new Narnia film depicting Susan fighting in the battles when she does not in the books at the CBMW and how the director argues that he want to represent secular opinion on women fighting on the front lines stating: "When the issue of Susan not participating in the fight for Narnia was introduced in the first film, I rejected it then. I was like, ‘Well if she’s just gonna make sandwiches then give her a plate and a knife.’ It’s something that I don’t agree with so I wasn’t going to make a movie like that."
As the CBMW highlights: Lucy is presented as a model of steadfast faith in the face of adversity. After she apologizes to Aslan for not obeying him the first time and announces her determination to follow him, he tells her, "Now you are a lioness. And now all Narnia will be renewed." Lewis chooses a female protagonist to play a crucial role (and not "just make sandwiches") in the overall effort to win back Narnia. It is difficult to see how anyone would not regard her as a "strong female character."
Unless, of course, women are only considered "strong" when they act like men.