Statecraft: If you use women to fight, and you are losing a long-term war. The ability to produce new soldiers for your nation is lowered proportionally to female casualties. In a generational war your side will continuously grow weaker. If the other side has women on the homefront who are giving birth to children, they will make up their war loses and have manpower for industry and further fighting over decades. Even if you win, your smaller population will soon be over-run by the breeding of your vanquished foes and you will be forced to fight again.