In 1914, the assassination of Archduke Franz Ferdinand-who was in line for the throne of the Austro-Hungarian Empire-propelled Europe into a war unlike any the world had ever seen. But it would take yet another remarkable series of events for the United States to decide to enter the fray, a century ago in April of 1917. By the time the armistice arrived the following year, empires had fallen and 15 million combatants lay dead. And for the United States, the consequences of the decision to get involved would reverberate throughout would come to be known as the American Century, and still echo today. Includes: How the actions of teenage Bosnian nationalists set the war in motion-and why European leaders could not (or would not) stop it The birth of modern warfare and the brutal results that came with poison gas, airplanes and tanks American leaders facing a future in which isolation is no longer an option How the underprepared U.S. military helped put an end to years of war-and emerged one of the world's great fighting forces Plus: the Versailles Treaty and the League of Nations and how they failed to avert an even more cataclysmic war two decades later