As long as we're going a bit off the beaten path, so to speak:
From Wikipedia:
"Before 1865, when the Thirteenth Amendment to the United States Constitution was signed, battles royal often appeared on the undercard of boxing matches. These fights would normally involve five or six slaves fighting blindfolded and bare-knuckled. Depending on the pre-agreed rules, these fights would either last until one man was left standing, the winner, or until two remained standing, at which point the blindfolds would be removed from the combatants and the fight continued until one was unable to continue. The owner of the winner would receive the prize, which was usually small.
The practice of fighting battles royal in this context continued long after the abolition of slavery. Some were still fought legally in the 1930s albeit with the use of gloves. However, most bouts in this period were fought illegally at "smokers", unsanctioned and unregulated boxing matches, as preludes to the main event. Almost all fighters at these contests, both legal and illegal, were still black African-Americans, although they were now allowed to keep their winnings. A battle royal is the subject of the first chapter of Ralph Ellison's novel Invisible Man.
Many major black boxers of the early 20th century gained their first in-ring experience at these battles royal. Such fighters include Jack Johnson, Beau Jack, and Joe Gans."