In the early 20th century, prizefighting was even more uncivilized than it is now. While fights between Black boxers and white boxers drew crowds, heavyweight title fights were segregated. There was the "World Heavyweight Champion," who was by default white, and a separate "World Colored Heavyweight Champion." It was easier to assume white superiority when they didn't fight each other. But Jack Johnson worked for years to get the chance to fight heavyweight champion Tommy Burns, and defeated him in 1908. Former champ Jim Jeffries was brought out of retirement to win the title back.
Their fight, hyped as the "Battle of the Century," took place in Reno, Nevada, on July 4, 1910, in front of 20,000 mostly-white spectators and nine motion picture cameras. Throughout the nation, many thousands more listened to live telegram bulletins of each round. Johnson beat Jeffries easily, and, as a result, racist mob violence broke out across the country, and Black Americans celebrating Johnson's win were attacked, and some were killed.
The fight was filmed, the film was banned, and therefore became the movie everyone wanted to see for years afterward. Vox has the story.
[via Damn Interesting]