[3][4] He was also a world-record-holding breaststroke swimmer, a decorated World War II Marine officer, an academic in educational administration, and an author of books on kendo, the culture of Japan, and the history of the Ryukyu Islands.
Warner grew up among Nisei in Long Beach, California, and began watching Samurai cinema and studying Japanese martial arts as a teenager.
At the urging of two senior officers, lieutenant colonel Anthony Biddle and captain Chesty Puller, he traveled to Tokyo in 1937 to continue his studies in Japanese martial arts.
In an exhibition event of the Palama invitational swim meet in Honolulu in 1939, he set the world record for the 220-yard breaststroke, previously held by Leonard Spence, with a time of 2:51.5.
[6] With Benjamin Hazard he helped found two of the first post-war Kendo groups in the US, in Berkeley in the spring of 1953 and again in Oakland, California in the fall of the same year.
[3] In 2001 the emperor of Japan awarded him the Order of the Sacred Treasure, 3rd class, Gold Rays with Neck Ribbon, for his accomplishments in the martial arts.