First of all, this case first involves nine masters, Ren Ji 'an and Liu Ba 'nv. It was Yan Ji 'an who made the mistake, and Liu Ba 'nv who took the fall for the Zhang Wu brothers. It was a trivial matter in the society at that time that a Wang gang would be beheaded if he took the blame. After all, the more they hit each other, the more they get hurt. But what Yan Ji 'an and Liu Ba-nu didn't expect was that Zhang Wu-ge had friendship with Yin Zhen and Huang Tianjun. Well, when the two princes heard about Zhang, they knew that saving Zhang not only saved their shame in Jiangxia town, but also punished two young masters. Not only that, at that time, the prince was in charge of punishments, and he could let the prince take the blame. So Yin Zhen, the old four, and Huang Hong, the old thirteen, joined forces to make a big deal out of it.
So Emperor Kangxi knew his brother Zhang Wu. In his later years, Kangxi was very tired of official corruption and the king taking office. The problem of heirs has been puzzling Kangxi. And most people like their children and grandchildren to enjoy family happiness around their knees in their later years. So from the perspective of an old father, Kangxi likes people who are filial. And Zhang came out to take the fall for his father only because his father owed Liu Banv kindness. This moved Kangxi.
Kangxi was a wise emperor, and he had his own prejudices. After consulting with the old three and the old four, before Zhang asked for a commission, the old four and the old four ran to Kangxi and truthfully reported everything about Zhang, including Jiangxia Town, including Liu Ba's daughter, including Alan and the situation. From the conversation between the old four and the old three, Kangxi may not know the truth of the matter, but he knows that this Zhang Wu brother is tied to the forces of the old four and the old eight.
On the other hand, Kangxi felt that Zhang was very filial and kind and could be used by future emperors.
Therefore, whether from the general idea of Kangxi's old father, or from the fact that Zhang was involved in two major forces to seize power, or to reserve talents for the future emperor. Kangxi felt that Zhang was worth saving and deserved his own courtesy, so Kangxi personally went to the altar to save Zhang.