Well, a movie like six and the city is primarily targeted women, I don't say all women likes them Sure you can focus on a woman in those kind of movies, it just doesn't happen often. War themed movies, as I said above, are typical male oriented. I was just presenting a point, why it is, one may see fewer women in movie than men. Don't ask me, about why they make males the primary figures in most of those movie, ask the movie makers
But aggression, war, feudal war settings, gangs (whether they be gangsters or any collection of criminals) and violence are typical associated with the male masculinity. I'm not saying that a woman can't possess those abilities (I know a few that fit that bill! and yes, pun intended) it just lend itself more natural to select a man having those qualities. And having a single woman as the main role, in for example a war movie, wouldn't raise the number of womens any way, since the rest of the cast, would then be primarily males anyways, unless you make an amazon like movie. There are also very few famous female warleaders compared to men. And those famous, have already had their movies done (Cleopatra and Jeanne D'Arc comes to mind) Then you have a movie like The English Patient. Here both male and female are lead roles, but then we are moving away from an overall war themed movie, with the focus on the romantic drama.