I’ve always thought it a little funny in an ironic way that if you actually look at competitive achievements of the rest of the show jumping team during that era, GM was basically the least accomplished. He rode on the USET from 1958 until maybe just after the 1960 Olympics, turned pro to coach, etc. but aside from riding on The Team, individually I don’t think he actually did anything big competitively. EDIT to add: Yet he’s the one who basically marketed himself into being this guru. As someone who didn’t start paying attention to English riding/the sporthorse world generally until approx. 2010, by the time I was actually in the horse world more, he was this crotchety old hunter/jumper curmudgeon who was the subject of a ton of memes (didn’t at least one blog style horse site start spoofing Chuck Norris jokes into George Morris jokes?) which, in hindsight was utterly inane. He was like, this, vaunted god of the hunter/jumper world and frankly no single person should be elevated to such a status in a sport.
Steinkraus was the first rider from the US to win an individual gold at the Olympics in '68, etc. and Chapot was also accomplished (not as familiar offhand w/Chapot’s competitive record to have anything specific to cite past “he won a lot of things”)
I’ve read Steinkraus’s books, “Riding and Jumping” and “Reflections on Riding and Jumping” and I’ve read “Hunter Seat Equitation” and I’ve read “The De Nemethy Method.” There wasn’t anything in GM’s oh-so-famous book that wasn’t in Steinkraus’s or De Nemethy’s work and Steinkraus was hands-down better at explaining everything in writing, IMO. (I mean, Steinkraus, IIRC worked as a book editor.)
(I’m not old enough to have been around in Ye Olden Days but I’m kind of a show jumping history nerd. I’m not a hunter/jumper rider either, always leaned more to eventing but never had the chance to actually do it when I was actively riding and these days I’m horseless and barnless.)