At the close of the 19th century, thousands of spectators gathered in secrecy to watch two heavyweight Irish fighters slug it out for 75 rounds. John L. Sullivan, boxing's first modern heavyweight world champion and the first to earn more than $1 million, took on challenger Jake Kilrain in a makeshift boxing ring on a farm in Richburg, Mississippi on July 8, 1889. Almost 3,000 people secretly traveled to the makeshift venue to watch the fight, paying as much as $15 for ringside tickets. Fans had traveled under cover of darkness the night before the fight, while their train tickets...