I'm writing this based on the "official" middle school history book where I was raised (due to historical reason the history book ends at 1949 so it won't offend any then current government in Taiwan and Mainland).
The PRC curriculum? You often mention Chiang, but what about Mao? What was he doing at this time?
1) Russia and Japan's hostility goes way back, so far back many Russians blame their empire's collapse to their loss to Japan in Siberia and their control of North East China (a huge piece of land was lost from China to Russia back then, and then to Japan, and then finally some part of it back to China). If you ever see the photo of Abe visiting Putin you'll see Putin greeted Abe with a pit bull or similar, and Abe was playing with that dog like a friend's house pet.
There has always been varying degrees of hostility between Japan and Russia/USSR including border clashes. But the collapse of the Russian Empire happened in 1917 and the Russians lost very little in terms of land to the Japanese. The Russians still controlled Siberia and basically only lost the ability to block Japanese expansion into places like Korea...
2) KMT back in the Sun Yat Sen's day (the brother in law of Chang Kai Shek) was actually very pro Japan. Back when the Manchurians' Qing dynasty was still around, students went to Japan for college, and formed the revolutionary militia who later became the KMT / Revolutionary party. After Sun Yat Sen's death there's a power struggle between the pro Japan Wang Jingwei fraction and the pro America Chang Kai Shek fraction. The party actually split in 2 during WW2 after the capture of Nanking (the former capital). As expected the Wang's fraction surrendered and resume civil government operation while Chang's fraction retreated to fight. At the same time these 2 fractions send assassins to each other, and at the same time fighting the USSR backed CCP led by Mao. As you might expect in this 4 way war, Japan easily captured a lot of area very quickly, and many of the civilians got very upset about how incompetents were their warlords.
You keep mentioning Chiang and he doesn't have the greatest reputation in the US/West nor the East. Some is deserved and some is unfair. But WGAF about his "brother" and his supposed sympathies for the Imperial Japanese? Yeah, okay, did that prevent China from resisting them and suffering massive casualties?
I also notice as stated above you never mention the elephant in the room named Mao. What was he doing during the Japanese invasion of China? Sort of resisting and cooperating with Chiang and the Nationalists. But also hoarding a large portion of his forces and sitting them out from the fight so they could attack the Nationalists after the then inevitable IJA defeat and retreat from China while Chiang, a very imperfect prick in his own right, gave pretty much all as singularly resisted the Japanese despite whatever trivial crap you want to tripe here...
3) Japan's puppet nation in the north (Manchuria), figure headed by the former empire of Qing, was captured by USSR right before Japan surrendered, with industrial infrastructure striped and sent to USSR. The location was hold by USSR and then given to Mao and became the base where CCP advanced southward.
Pretty much Soviet policy at the time, take the war booty to offset your massive losses in men and material. It wasn't their first dance against the arrogant IJA, an army that was completely devoid of strategic maneuver or tank/antitank capabilities...
4) Due to the power struggle between Chang's and Wang's fractions, many of the KMT military eventually defect to Mao, including the officers from the famous Whampoa Military Academy (sort of like the West Point in the US). Chang was not a competent military leader and he prioritize his own power over his military campaign. He had a tendency of imprisoning or executing his own generals when they became too influential or seen as a rising star in foreign political circle (this continue well into his days after retreating to Taiwan). Oftentimes he would use generals he could trust but lost the entire force, running away from the post, hiding in the mountain instead of at the frontline, etc. Chang and his family was also famous for being very corrupted (according to Truman's note). What's more? He passed his presidential position to his son after he died (fortunately his son was actually a very competent and good politician who laid the good foundation of today's Taiwan).
Yeah um the above is just a lot of simplistic BS. Yes some defected and all that, but one of the main reasons the Nationalists lost the civil war with Mao's communists was war weariness. The Kuomintang with all of their failings, resisted the Imperial Japanese to the bitter end while the PRC rested large parts of their forces with a nod-wink at Japanese forces enjoying implied truces. The Kuomintang Nationalist Army suffered massive losses of men and material had to be rebuilt several times over. Not that the PLA didn't, but they rested large parts of their "guerilla army" and they were waiting to pounce once the Japanese withdrew.
As far as "Truman's note", a lot of that racist bias came from US Army Gen. Stillwell, the main US commander in the theater who was a bit of a notorious prick and pretty much unliked by everyone from those in his own command to the British and of course Chinese. He did some good things and had organizational talents, but he was very limited in strategic vision and Chiang was in fact probably the better leader that actually understood how to withstand the Japanese onslaught and maintain control. And of course Truman needed a scapegoat for the fall in 1949, but of course things simply aren't that simple. Both Stillwell and every US political leader failed to grasp that Chiang was fighting a two-front war. One against the Japanese, the other against the PLA. The PLA was basically fighting one while pretending to fight the 'other'...
The internal arrangements of a submarine are incredibly complex and the sorts of allowances and accommodations necessary to permit a change of this magnitude would be huge.
