The uneasy negotiations between the United States and Iran are unfolding under the shadow of a long historical truth: great-power systems rarely collapse in a single dramatic moment. They erode. They drift. They unravel—through hesitation, miscalculation, and the quiet accumulation of small crises that go unanswered until answering them becomes catastrophic. The European descent into war in the 1930s remains the starkest example of how incremental provocations, when met with divided or delayed responses, can push nations toward a confrontation none of them originally sought. As the historian A.J.P. Taylor observed, WWII was a war that no one willed, planned,...