St. Louis Cardinals pitcher Mike O’Neill hits the first pinch grand slam ever in the majors, against the Boston Beaneaters. He also becomes the first pitcher in the National League to hit a grand slam in the 20th century. The hurler’s ninth-inning blast off Beaneater Togie Pittinger proves to be the difference in the Redbirds’ 11-9 victory over Boston at South End Grounds.

This Day In Baseball

On June 3, 1902 — St. Louis Cardinals pitcher Mike O’Neill hits the first pinch grand slam ever in the majors, against the Boston Beaneaters. He also becomes the first pitcher in the National League to hit a grand slam in the 20th century. The hurler’s ninth-inning blast off Beaneater Togie Pittinger proves to be the difference in the Redbirds’ 11-9 victory over Boston at South End Grounds.

Source
Baseball Reference June 3