You clearly don't understand what people are speaking about here. We KNOW they were at war, but the battle comes out of no where. They mention they are sending her there, then they have an entire chapter between that, and a few pages into another chapter suddenly it's war time.
@pizzalion she got tortured, mentally broken and brainwashed. So it's understandable why she still stays with the bad guys now she has her "liberty" back.
This is the problem with most isekai authors, either the MC or the villains are shown to be ridiculously broken in the first few chapters. Oh well, I'll keep reading