Berlin, you are just questioning the correct meforesh for # i?:
i. Radvaz: Women do not fight, due to “Kol Kevudah.” Rather, a Kalah leaves the Chupah, i.e. she forfeits the week of Sheva Berachos because her husband must go to fight. Alternatively, women supply water and food for their husbands, like Aravi women do nowadays.
ii. Sefer ha’Chinuch (Mitzvah 603): Women do not fight in war.
iii. Question (Minchas Chinuch): What is the source to exempt them? This is an Aseh that is not Zman Grama!
iv. Rambam (introduction to Sefer ha’Mitzvos DH v’Atah): Women are exempt from optional wars.
v. Rashash (Sotah 44b b’Mishnah): It is a Chidush that women go. Perhaps they go to prepare food for the men.