Henry F. Callenberg

From Hoopedia

H.F. Callenberg was a physical education professor at the University of Iowa in the late 19th Century. At the time basketball was generally played with seven to nine players per side. He is credited with scaling the game down to a five-on-five game. The first college basketball game with five players to a side was played before 400 spectators at the Iowa Armory when the Iowa Hawkeyes hosted the University of Chicago on January 18, 1896. Chicago squeaked by with a 13-12 win. Callenberg refereed the game. Amos Alonzo Stagg coached the Chicago team.

Kallenberg had met Stagg at the International YMCA Training School in Springfield, Massachusetts, where the two of them were students in 1890. In December 1891, James Naismith, director of physical education at the school, invented the game of basketball.