Of all the popular myths about “how the world works,” the most dangerous to us at this moment is the one that goes “peace is normal, war is an aberration.” Truth is, war is normal and peace very unusual. We’ve lived through a happy time, ever since the Second World War. Thanks to American superpower, and the destruction of the totalitarian regimes in Rome, Berlin and Moscow, we’ve had a happy period of relative peace. Very few big wars. Little genocides (China is exceptional, but they changed to accommodate the global pattern). Deterrence (as in “mutual assured destruction”) mostly worked.
That was a rare time. Now we’re getting back to normal.