"Regrettably, Anson used his stature to drive minority players from the game. An 1883 exhibition game in Toledo, Ohio, between the local team and the White Stockings nearly ended before it began when Anson angrily refused to take the field against Toledo’s African-American catcher, Moses Fleetwood Walker. Faced with the loss of gate receipts, Anson relented after a loud protest, but his bellicose attitude made Anson, wittingly or not, the acknowledged leader of the segregation forces already at work in the game. Other players and managers followed Anson’s lead, and similar incidents occurred with regularity for the rest of the decade. In 1887, Anson made headlines again when he refused to play an exhibition in Newark unless the local club removed its African-American battery, catcher Walker and pitcher George Stovey, from the field. Teams and leagues began to bar minorities from participation, and by the early 1890s, no black players remained in the professional ranks."
https://sabr.org/bioproj/person/cap-anson/