Comment by b0rsuk

I think people setting these up get their inspiration from the agoge, the boy rearing system in Sparta. The same methods are used to raise children soldiers in Africa.

https://acoup.blog/2019/08/16/collections-this-isnt-sparta-p...

Also, you might be interesting in Cult of the Badass:

https://acoup.blog/2021/02/19/collections-the-universal-warr...