Was recently at war with a nation who attacked 5 members of my alliance, and then found himself attacked by another nation (me), I was quite surprised when I woke up this morning and he was gone...
I'm quite annoyed that he was able to do a fair bit of damage, and yet he doesn't get the full beatdown and we don't get to take his stuff. In *cough* another game *cough* it is not possible to delete your nation mid-war, at the very least it shouldn't be possible to delete your nation during offensive wars; if you want to attack other people you should actually have to sit through the whole thing.
On another note, even if this has to be a thing, there was no notification or anything that the war had ended, and worse all record of the war seems to have disappeared, although the infra I lost is still gone, which seems weird.