This is footage from the 45th annual Junior Boxing Program Championships, held in 1964. From History’s Playlist:
The Naval Junior Boxing Program was founded in 1919 by Spike Webb, and was made available to the children of naval Officers and cadets stationed in Annapolis, MD. Children ranging in age from 5 through 11 and weighing 30 to 100 pounds were allowed to enter the ring and fight during these tournaments… This youth boxing club was meant to teach the children sportsmanship and how to have a strong body and mind under pressure.
(via Weird Universe)