John Boyd may be the most remarkable unsung hero in all of American military history. Some remember him as the greatest U.S. fighter pilot ever-the man who, in simulated air-to-air combat, defeated every challenger in less than forty seconds. Some recall him as the father of our country's most legendary fighter aircraft-the F-15 and F-16. Still others think of Boyd as the most influential military theorist since Sun Tzu. They know only half the story. Boyd, more than any other person, saved fighter aviation from the predations of the Strategic Air Command. His manual of fighter tactics changed the way every air force in the world flies and fights. He discovered a physical theory that forever altered the way fighter planes were designed. Later in life, he developed a theory of military strategy that has been adopted throughout the world and even applied to business models for maximizing efficiency. On a personal level, Boyd rarely met a general he couldn't offend. He was loud, abrasive, and profane. A man of daring, ferocious passion and intractable stubbornness, he was that most American of heroes-a rebel who cared not for his reputation or fortune but for his country.