To put it bluntly, in order to preserve our strength, we decided to go for the best policy. In the TV series, when Zhang Xueliang and others were discussing the retreat, Zhang Xueliang just received an order from Chiang Kai-shek to retreat, thus throwing the guilt of fleeing without fighting to Chiang Kai-shek in the future. The fall of the three northeastern provinces became the ultimate victim of this political struggle.
In other words, no matter how powerful the troops are, they really can't play any role if they are placed in the hands of people with ulterior motives. Therefore, the stigma of the Northeast Army fleeing without fighting should also be borne by those who violate morality!