What do you define as peace??? Peace can mean many things. Peace in the political sense of just no war? Or peace as in a state of mind? One could be in a war zone but also at peace with themselves or their reality, though of course that's easy said than done when you live under the terror of war and all the troubles and dangers that come with it.
You're right, having peace could come in from any dimension, however, above all, we need peace of mind to help us have peace at every other aspect of life we may be facing, it is because people are not having this same peace of mind that makes some acted in such a way that they do no care about the consequence of other things they are doing which could be at the detriment of other ones.
War could emancipate from difference human challenges and one of which is the lack in peace and serenity, for one to lose, they will believed that its more better for others to lose along with them, there are other personal challenges that causes this same thing, but when we all have each others in mind, then we could be our brothers keeper and will not accommodate on anything that could deprive us from having peace form within and without.