Why is it the most wise for Cao Cao to let all seven daughters marry one person?

Because doing so can not only interfere in state affairs, but also give Xian Di a reassurance and finally protect his family.

It may be a shame for modern people that Cao Cao married seven daughters to the same person. But in his environment, it is a very clever thing for Cao Cao to marry his seven daughters to the same person. For example, Cao Cao's cleverness can be seen for several reasons.

At that time, the Han dynasty always had the tradition of the dictatorship of consorts. At that time, Cao Cao never claimed to be the emperor, but married his daughter to Emperor Xian of Han Dynasty, which not only gave Cao Cao the power to take charge of state affairs, but also left him a good reputation. That is, although he is in charge of the internal power of the imperial court, he has no intention of being the emperor. In the eyes of those people in the Han Dynasty, Cao Cao was not a real rebellion.

The second is to give Emperor Xian of Han a reassurance, because Cao Cao was very kind to Emperor Xian of Han a long time ago, so Emperor Xian of Han always trusted Cao, but when the Tang Dynasty really became Cao Cao's world, no matter which emperor changed, there would be a gap in his heart and he wanted to get rid of him. When Cao Cao married his daughter to Emperor Xian of Han Dynasty, he showed a feeling that "your daughter is in your hand, and I don't touch you, but I have been helping you".

Finally, on the one hand, in order to ensure the safety of family members, the situation in the three countries was very turbulent at that time. Cao Cao knows that the world is not peaceful now, and his opponent is likely to call at the next moment. But even if his opponent Liu Bei and others call, because he occupies the reputation of the imperial concubine, even if there is a catastrophe, at least he can ensure that his family can leave some people behind.

I have to say that Cao Cao, as a lean man, is very skilled in both military and politics.