Ethically, it’s just flat wrong to send the women to fight unless the only remaining males either need a cane to walk or don’t need to shave.
Practically, the average female is just not as physically capable of combat as the average male. Why knowingly include the less-capable in a force that your very survival may depend on?
Not even all males are capable of meeting military physical standards for enlistment or induction. Those minimal standards are put there for a very good reason. In the Army and Marines feet issues for example can exclude you from service.