sentences:  Among the fifty or so boxers that participated were triple World Champion Henry Armstrong, Callahan's opponents Jackie Fields, Ace Hudkins, and Jack Silver as well as Young Jack Thompson, Abe 'The Newsboy" Hollandersky, Fidel La Barba, ex-Middleweight champion Al McCoy, Jim Jeffries, and Maxie Rosenbloom.Callahan worked in the movie business in his boxing retirement.He did stunts for at least four movies in which he did not appear, and worked on the crew, often as a technical adviser for at least ten movies, many with boxing themes.