One of Zhu Yuanzhang's laws is about "Jingnan". In order to ensure the normality of the imperial court, if the treacherous court officials make an insurrection, the vassal king can lead his troops into Beijing to be diligent, so as to "make the country peaceful." Judy seized this point and launched the "Jingnan War". However, there is still a rule in the formation of Taizu, that is, before the appearance of the captaincy, the emperor summoned the captaincy, and he must leave Beijing within five days after successfully eradicating the treacherous court official. So this is just an excuse for Judy to take the throne.