The pictures show an old-school baseball game, typical in every way save one: Everyone wears a mask. There’s a face mask on the hitter, the bench and the crowd. Underneath their standard equipment, the umpire and catcher have them, too.
This is how the Pasadena Merchants and Standard-Murphys played a game in the Southern California Winter League on January 26, 1919. The influenza epidemic that had started the previous year was spreading, and California was concerned. Pasadena had started requiring residents to wear masks in public; on the first day that the rule went into effect, the city made 60 arrests to show that the new law was for real.