Looking back at the feudal dynasty of China, history shows us one emperor after another, some of whom have built up the country from the horse, created a new dynasty, and some of whom have successfully succeeded to the throne and continued to create a prosperous era.
In the monarchy system, the one who is most concerned about is the crown prince, besides the emperor, the emperor who is most concerned about is the crown prince. As the next heir, this position is what almost every prince dreams of.
For this reason, in history, we can see how many brothers turned against each other and finally met each other in order to compete for the throne. However, even if this position is attractive to everyone, there is only one winner, and the decision is in the hands of their father, the ruler of the world.

Looking back on history, when it comes to choosing the next prince, the emperor almost always chose to establish legitimate to establish chief, because in feudal royal power, the matter of the superiority of legitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illegitimate illeg
Even if there may be a better son to serve as the crown prince, the emperors will choose the legitimate son as the crown prince and carefully cultivate the way of governing the country since childhood.
For example, the Zhu Yuanzhang , after creating the Ming Dynasty, he made his legitimate son the crown prince, and he always taught him how to govern the country. However, after the prince passed away unexpectedly, he made his grandson Zhu Yunwen the next heir.
Among his many children, Zhu Di is the most like him. He has been good at literature and martial arts since childhood and has a way to govern the country. However, because he was the second son, Zhu Yuanzhang never regarded him as his next heir and has always trained him as a general.
This also led to Zhu Di's later rebellion, and he took the country from his nephew. There are many princes like this who only established the eldest son and then rebelled. There were several in the Tang Dynasty. The most famous one was Li Shimin who took the throne from his brother, and there was also Li Chengqi who automatically gave up the throne and gave up the position of prince.

Li Chengqi, Tang Ruizong Li Dan's eldest son, and Li Dan is the son of Wu Zetian . His life was also legendary. He ascended the throne twice, and rejected the throne of emperor many times. It can be said that he had no preparation for the throne between the two times and had to go there.
Li Dan was not Emperor Gaozong of Tang Li Zhi's eldest son. Li Zhi had 8 sons in total, and Li Dan was the youngest son. Logically speaking, when the concept of establishing a legitimate and a eldest son was very serious at that time, he could not be the crown prince no matter what.
But God seemed to be joking with him. His brothers were either demoted to prince by the then queen Wu Zetian when they were still the crown prince, or were retaliated for their biological mother. Some even more, after ascending the throne, they were demoted to prince and sent to the fiefdom because of their bad relationship with Wu Zetian.
Later, Li Dan became the emperor, but he was unable to take power. The government was basically in the hands of Empress Wu. As the emperor, he was still restricted everywhere and eventually gave way to Wu Zetian.

Later, Wu Zetian was about to abdicate, but Li Dan did not want to continue to be the emperor, so Wu Zetian passed the throne to Li Xian , but soon Li Xian was poisoned to death by his own queen Wei. Wei also wanted to follow Wu Zetian and wanted to kill Li Dan. In the end, the news was learned by Li Dan's second son Li Longji , and secretly killed Empress Wei and helped his father get the throne back.
Li Dan then became the emperor again. When Li Dan succeeded to the throne for the first time, he enthroned his eldest son Li Chengqi as the crown prince. However, although Li Dan was the emperor at that time, he had no real power and had been under Wu Zetian's surveillance. At the same time, Li Chengqi, as the crown prince, was naturally not spared.
Later, Li Dan was deposed and Wu Zetian ascended the throne, but suddenly put Li Dan in house arrest in the Eastern Palace, but he did not have the position of prince. So, the nightmare of Li Dan's family came.
Wu Zetian ascended the throne and became emperor. No one knows whether she will return the country to the descendants of the Li family in the future. At this time, Li Dan, who once became an emperor, became a thorn in the eyes of many people. His children were also trembling every day and lived in the shadow of Wu Zetian every day. At that time, the five brothers of Li Chengqi were together almost day and night, fearing that they would be assassinated after being alone.

This also made the Li Chengqi brothers have a good relationship later.Later, with the help of his younger brother Li Longji, Li Dan ascended the throne again, although his father Li Dan always wanted to make him the crown prince again.
However, Li Chengqi refused many times and insisted on giving way, allowing his younger brother Li Longji to become the crown prince.
Later, Li Dan conferred Li Longji as the crown prince, and soon after, he took the initiative to give way and passed the throne to Li Longji. After Li Longji ascended the throne, he was still very close to Li Chengqi's brothers and others, and he also rewarded Li Chengqi with gold, silver and treasures many times.
Although Li Chengqi did not become the crown prince, his life was very comfortable, he was not in conflict with the world, did not participate in the government affairs, and became a free prince. After his death, he was posthumously named emperor by his younger brother Li Longji.
Although Li Chengqi resigned from the position of crown prince and gave up his rights, he was friendly and respectful. He did not lose his family affection because he was born in the royal family, and he lived a comfortable life in the second half of his life. If he had accepted the position of prince at that time, a tragedy like the change of Xuanwu Gate in might have happened again, and the tragedy of will be reappeared.