solarz
Brigadier
Chiang Kai-shek avoided direct resistance to Japan from 1931-1937 because he feared it would trigger a full scale invasion of China, which China was in very poor shape to fight. Moreover, he feared the Communists were a greater long-term threat than Japan. Do you think that if Chiang had committed his full army to fighting Japan in 1931 that Japan would not have invaded China?
The balance of forces between China and Japan was just as imbalanced if not more so in 1931 than 1937. Nobody knew that Japan planned a full invasion and colonization of all China in 1931. There was a huge risk to launching a full scale defense war against a more powerful enemy if that enemy has limited goals that could be enlarged. In the Korean War: the Communists almost lost the whole peninsula when they gambled and bet everything on conquering the South. The South had no desire to conquer the North, but when Kim Il-Sung tried to change the status quo, he nearly lost everything. That was Chiang's mindset: the Japanese occupation of Manchuria was bad but starting an all-out war could make things a lot worse.
The Japanese considered Chinese (and all other non-Japanese Asians) to be lesser races long before 1937. In fact it was the stiff Chinese resistance at Shanghai that shocked them. I've read that the Nanjing Massacre was partly a desire for revenge at taking so many casualties in Shanghai and partly to shock China into surrendering since Nanjing was the capital. Racism was a big contributor, but as you said the Nanjing massacre was unique even for the long, brutal war.
I would say Jiang's biggest mistake was not recognizing the extent of Japanese ambitions. Had he committed to full out war against Japan in 1931, the Japanese military would not have gained as much momentum as it did later on.
After all, let's examine the historical facts. Due to Jiang's decision to all but abandon Northern China to the Japanese, the Japanese gained a vast human and material resource pool from which to fuel its war machine. In exchange, Jiang gained the time to train a few elite divisions which he lost in the battle of Shanghai. I would say that is a very poor trade-off.
I completely disagree with your assertion that "nobody knew Japan planned a full invasion of China in 1931". Many people knew, from intellectuals to military officers, though it is also true that many others (including Jiang) chose to bury their heads in the sand.
As for the Nanjing Massacre, you need to understand that Imperial Japan had wholeheartedly embraced its samurai culture. It respected those who were strong and despised those who were weak. Like I said, why did the Japanese leave Shanghai relatively untouched while conducting wholesale slaughter in Nanjing? My opinion is that Shanghai resisted fiercely, while Nanjing capitulated without a fight.