John Boyd was arguably the greatest fighter pilot in American history. From the proving ground of the Korean War, he went on to win renown as the instructor who defeated-in less than forty seconds-every pilot who challenged him. But what made Boyd a man for the ages was what happened after he left the cockpit. A fighter on the ground as well as in the air, Boyd was relentless, brilliant, stubborn, and virtually always right. He managed to transform almost single-handedly the way military aircraft, in particular the F-15 and F-16, were designed. He then dedicated many lovely years to a radical theory of conflict that at the time was mostly ignored but now informs military activity around the globe and is acclaimed as the most influential thinking about conflict since Sun tzu's The Art of War.