"I can lick any son-of-a-bitch in the world." So boasted John L. Sullivan, the first modern heavyweight boxing champion of the world, a man who was the gold standard of American sport for more than a decade, and the first athlete to earn more than a million dollars. He had a big ego, big mouth, and bigger appetites. His womanizing, drunken escapades, and chronic police-blotter presence were godsends to a burgeoning newspaper industry. The larger-than-life...