I'm so happy it's not a heart wrenching battle. with the slave collars, at least they don't have to kill those "dead roots".
but they really didn't say anything prior, Souma didn't even narrate the acquisition of "slave collars", the war was foreshadowing something but to end it like this. I suppose gore isn't good in any harem story... I'd rather shed tears than underestimate a good story.
this is a good result nonetheless, they don't have time to be gore-like, the fronts are divided and they have to make it like a BOSS