What is Peace?

What is peace? Chapter 12 in Book XIX of The City of God proposed a view of peace that I had never considered: that peace is what every person strives for and because it is everyone's ultimate goal, the manifestations of peace can be vastly different depending on people's differing perspectives. St. Augustine goes on to define several of the different types of peace which exist in the world. Perhaps the most difficult for me to grasp when first reading it was the idea that even war is a form of peace or rather a quest for peace. At first, this seemed like a paradox: how can war be peace? But upon further analysis, St. Augustine’s interpretation of peace is completely logical. Augustine writes “Thus their desire is not that there should not be peace but that it should be the kind of peace they wish for” (866).
Can utopia exist when if someone wishes to change that utopias peace? Augustine writes “In fact, even when men wish a present state of peace to be disturbed they do so not because they hate peace, but because they desire the present peace to be exchanged for one that suits their wishes” (866). So what if someone living in a utopia wished to change the present peace? The example that comes to mind is Omelas and the people who leave because they disagree with the treatment of the child. What if rather than simply leaving, they wished to change the current state of peace? War and utopia don't seem to coincide with each other. If two utopias were at war, the result would be each becoming a dystopia. To avoid dystopian consequences, I became curious of whether there was a “right peace” and a “wrong peace” and if The City of God held the answer.
What is St. Augustine’s definition of Godly righteous peace? 
The answer, as far as I could discern, is that there is “earthly peace” and “eternal peace.” Earthly peace is when man “observes” two things: “to do no harm to anyone, and, secondly, to help everyone whenever possible” (873). Augustine’s idea of peace opposes Plato’s definition of justice because he concludes that justice is not “meddling” in other people's lives. Augustine also states that earthly peace is to be on a pilgrimage towards eternal blessings and peace. One question I had is as follows: is there no such thing as “true” earthly peace, but rather one must accept that a real sense of peace will only come when a person enters the Heavenly City?