You are making unwarranted assumptions in your analysis I suggest. Not all members of the military have to be in the front line. There is a significant support element. There is no reason I can see why women should not serve as ably as men in all branches according to their capabilities in the same way men do. In my own specialisation, around 40% were women and their gender was never an issue. The best boss I ever had was a woman.
I have seen a female accounts officer disarm 3 men while armed with nothing more than a piece of metal conduit. Never judge a book by its cover.