Genmotty said:
It's a good question without quick answer....
The armed forces having already achieved its victory had to give way to economic concessions on the Asian mainland...
[Japan was still] a mainly agricultural sectors with little precision manufacturing industry.
That does explain the lack engineering depth, & I agree, Manchuria was an issue. I don't think it was by any means the only issue. I suspect part of the reason is, Japan was trying to make up more than 200yr of industrialization in so short a time.
I will agree, it limited the ability to produce modern weapons, which influenced doctrine; I do think part of the reason for increased emphasis on moral over material was precisely because Japan simply couldn't produce better weapons.
Genmotty said:
So throughout the 1920s with the Military budget spending growth rate decreased we don't see Japan taking onboard many of the developments that European nations took from the lessons learnt in the Great War...much because Japan didn't fight in the trenches or had fought a major war in Korea or Southern Manchuria.
The key example being them totally 'not getting' the concept of an infantry submachingun when they had example copies and had the expertise to build them. They simply hadn't 'got' the effect it could have on the battlefield
That really doesn't address the issue. That's a symptom, not a cause, IMO. The senior officers were poorly trained & educated in both services. Quality of leadership was the worst I've ever heard of.
IMO, it's
because the SOs were so awful the doctrine was so bad: officers trained to blind obedience, & uneducated/untrained in examining other options (as Japan's were), do not produce flexible doctrines or plans. Officers without even the grasp of the difference between tactical & strategic victory


(& Japan's lacked it




) are incapable of developing doctrines & plans to cope with the situation Japan found herself it. And Japan's SOs simply did not understand the
enormous degree to which attacking Britain or the U.S. differed from attacking China or tsarist Russia, which is a product of poor education & training. (Contrast the Prussian General Staff model, IMO the best approach.)
Genmotty said:
In other ways their doctrine was very strong, at least in China, because it functioned well enough. It's shortcomings were clear later when the Soviets, British and Americans who had improved their millitaries throughout the interbellium fought with effectively a WWI force, that was fighting against effectively insurgents and not a comparable enemy.
That comes back to my suggestion the education & training was awful. Moreover, it calls in question the proposition doctrine was good, since the idea is for doctrine to be responsive to opposing armies & changing conditions. The German system was the best in the world that way IMO. Japan's was worst.
Genmotty said:
The regime was brutal at the top because the military got itself into power by political violence.
I think that goes deeper. That strikes me as a holdover from the
samurai era.
Genmotty said:
the brutality of Japanese soldiers is not all that important in comparison to their doctrine and equipment
I disagree. The change after WW1 was dramatic & was reflected both in treatment of POWs & in the attitude to death in battle. You may be right; the brutality at the top may have "trickled down". IMO, it's not that simple.
Genmotty said:
The Advance South policy was not only about resources, it was about the IJN wanting to stay relevant.
I'd agree with that, generally. (And with the IJN push for it.) I'd also say, tho, IJN's desire not to be marginalized was directly causal of the attack on Pearl Harbor, regardless what the excuses were.