History is littered with wars which everybody knew would never happen.

Powell’s aphorism is a warning against complacency and the false certainty of “it can’t happen here.” By pointing to the repeated historical pattern of supposedly unthinkable wars becoming reality, he highlights how collective assumptions, wishful thinking, and elite consensus can blind societies to accumulating risks. The line also implies that the very confidence that war is impossible may be part of what enables it—discouraging preparation, diplomacy, or deterrence until events outrun intentions. More broadly, it critiques the limits of prediction in politics and international relations: what “everybody knows” is often a fragile social belief rather than a reliable assessment of human conflict.