Forget the idea that the army has always been hetero and male

There's also Joan of Arc

https://www.dailymail.co.uk/news/article-2285841/The-women-fought-men-Rare-Civil-War-pictures-female-soldiers-dressed-males-fight.html

Wasn't it mainly because the men valued the women's lives more than their own due to a sense of duty to the protection of the innocent? When WW3 comes around, I'm putting my life on the line so women don't have to fight. No offense, but women do have more biological needs then men, like tampons, etc. Having a woman captured on the battlefield might mean a violation of a woman's chastity, as usually happens in violent wars.

This may come as a shock to you, but men captured on the battlefield also face the threat of sexual abuse. The problem is not the gender of the victims (or anything else about them): the problem is power and violence.