from Jigaro Kano was and still is a full featured combat discipline. Combat Judo served well as an official system of Japanese Imperial armed forces and police till the defeat of Japan in WWII.
In parallel with this Judo, Jigaro Kano made a push for Judo as a sport discipline that can be seen as a subset of his original version and it looks like in Japan both directions where persuade simultaneously.
After WWII, during American occupation, practice of combat Judo, in line with other actions by General MacArthur SCAP occupation administration to suppress strong militaristic traditions of Japan (such forcing to adapt the new pacifistic constitution and so on), has been forbidden.
I can’t advocate resurrection of Japanese militaristic traditions: the horrible atrocities committed by Japanese military in WWII are on a match with what been perpetrated by Nazi Germany. Perl Harbor attack is looks like innocent military operation compare to what has been done by
witch has never been prosecuted (credit to General MacArthur, President Truman, and American Military Tribunal).
So, Judo failed victim of changing nameplates with unwanted associations. It got pushed aside by
(it is just a non-Japanese peasant workout exercise from Okinawa) and
(it is an entirely new philosophically pacifistic meditation exercise that has nothing to do with that old
that has been taught to senior military officers and elite recon units; Isn’t it?).
The only way to survive for Judo in those circumstances was to purse the sporting model based on the foundation created by Dr. Kano prior to the war. It’s culminated in accepting
Judo as Olympic sport
discipline in 1964 Olympic Summer Games in Tokyo.
It is widely acknowledged that highly instrumental in this process was work by
(including his book
“Cannon of Judo”
Combat Judo in Kodokan
Evolution of Judo Contest Rules