> The form will be mandatory for men and voluntary for women.
In other words, it's functionally the same as Selective Service forms in the US.
Two, Germany, like most countries and frankly human populations, has a male surplus in its fighting-age population [1]. This is why, historically, large socities tended to wage war with men first. (Even those that e.g. held elite units in reserve, which undermines the usual biological argument.)
[1] https://en.wikipedia.org/wiki/Demographics_of_Germany#/media...
...why would you populate your army solely with the surplus? The point is you have a buffer that you can burn without immediately impacting your demographics for the long term.
> that is not the reason why men and not women go to war
It's a serious theory [1]. (It's more correct to say the surplus and it share a common cause.)
[1] https://link.springer.com/rwe/10.1007/978-3-319-19650-3_931
Made for a good story, reality is a bit more complex methinks. There's after all a lot of money to be made with war.
The "male surplus fighting-age population" in Germany will flee to the next European host or back to the MENA country they fled from if conscription begins.