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A century ago this month, Europeans stood on the brink of a war so devastating that it forced historians to create a new category: “World War.” None of the leaders at the time could imagine the wasteland they would inhabit four years later. By 1918, each had lost what he cherished most: the kaiser dismissed, the Austro-Hungarian Empire dissolved, the tsar overthrown by the Bolsheviks, France bled for a generation, and England shorn of the flower of its youth and treasure. A millennium in which European leaders had been masters of the globe came to a crashing halt. What caused this catastrophe? President John F. Kennedy enjoyed needling colleagues with that question. He would then remind them of his favorite answer, quoting German Chancellor Theobald von Bethmann Hollweg: “Ah, if we only knew.” When, in the Cuban Missile Crisis of 1962, Kennedy found himself “eyeball to eyeball” with Soviet leader Nikita Khrushchev, making decisions that he knew could mean quick death to 100 million people, he reflected on the lessons of 1914. At several decision points, he adjusted what he was inclined to do in an effort to avoid repeating those leaders’ mistakes.
Allison, Graham. "Just How Likely Is Another World War?" The Atlantic. July 14, 2014.