The conclusion of Ken Burns' profile of the renowned boxer (1878-1946) charts Johnson's “fall.” But as it opens he's undisputed heavyweight champ, having easily defeated Jim Jeffries on July 4, 1910. The victory sparked race riots, and it was clear that no white man could outpunch him. But whites “were going to exact their pound of flesh,” says boxing historian Bert Sugar. And the way to do it would be through Johnson's sex life. Then along came a “white hope” with stamina named Jess Willard.