I once read that in the past two thousand years, there may, repeat MAY have been a total of 20 years without war somewhere in the world. My person guess is that the 20 year figure is only that large because the historians didn’t know about a particular genocide in progress in some lesser-known corner of the globe. It is simply a part of life for every generation. Sometimes it happens to your country, sometimes to someone else’s country. The only end for it will be the Second Coming.
No matter what, the human condition will eventually reveal some sociopath that wants to be in charge.
We deduce the possibility of peace because there are intervals between wars.