Boxing grew in popularity at the turn of the century, but some viewed the activity as a moral vice. New York State outlawed public contests in 1900. Prizefighting took to private venues such as Sharkey’s Athletic Club, where George Bellows witnessed matches. The Knock Out foregrounds the violence of the sport, as a referee struggles to hold back the victor from further beating his fallen opponent. Bellows also emphasized the intensity of the fans, surging forward and reveling in the escape from polite social conventions.