The Dai Nippon Butokukai has kind of a checkered history and is, currently, a very minor organization in Japan without much real connection to the pre-war group of the same name. It appears to be somewhat larger outside of Japan than in.
There's a kind of interesting (if old) discussion here
The summary here
is a little better if you can read Japanese.
To get back to "peace", I think that before discussing peace in Aikido it should be established whether or not Morihei Ueshiba was in fact a pacifist (Kisshomaru denied that either he or his father were pacifists), and/or if he was a pacifist then what "peace" would mean to him.
Peace might, for example, mean something different to someone like Arnaud Amalric
than it does to most people here (or so I imagine!).
Sorry about the lateness of my response. Here you can find the History of DNBK and the international division of the organization. I wanted to post the whole article, however the material is copy righted, so I can only post the link:
Hope this clarifies the situation.