In five years of pro baseball, Mary Pratt threw a no-hitter, notched a 20-win season and helped lead her team to the league championship series, all while wearing makeup and above-the-knee skirts. Like everyone else in the All-American Girls Professional Baseball League, she was expected to follow a simple rule: “Look like women. Play like men.”

Ms. Pratt, who died May 6 at 101, was one of the first members of the Rockford Peaches, a powerhouse Illinois team formed in 1943 and immortalized in director Penny Marshall’s sports comedy “A League of Their Own.”

Although the Peaches and the All-American league folded after a dozen seasons, Ms. Pratt helped keep their legacies alive, appearing at baseball conventions and other events to champion women in sports.

“As some of the other former players will tell you, once she was on the stage you couldn’t get her off,” said Ted Spencer, former chief curator of the National Baseball Hall of Fame in Cooperstown, N.Y. “She was very dedicated to telling the story that young women and girls deserve an equal chance in all sports, not just baseball.”