A few years ago, I taught a course at Yale. Over dinners, I'd listen to my students talk about their other courses, and in many of these conversations there was one that stood out: Grand Strategy. For many students, this yearlong course was not just a class, but a life-altering event. Somehow students in Grand Strategy were applying Thucydides, Kant and Sun Tzu to modern foreign policy crises. They talked excitedly about seeing the connections between big ideas and big events. Grand Strategy is taught by three great professors - John Lewis Gaddis, Paul Kennedy and Charles Hill. But when...