In the history of the Tang Dynasty, Li Shimin was unanimously recognized by later generations as the emperor of the qin dynasty, Han Wu and others, and his descendants Li Longji was even more famous than the famous emperor li longji, although he was dim in his old age, but Li Longji when he was young, in today's words, is a completely outstanding young man. Speaking of Li Longji, we have to mention his father Li Dan, Li Dan's achievements in the history books are not obvious, and he can even be called cowardly, his throne is also his son to help him win, without Tang Long's coup, Li Dan is still just an idle prince far away from Chang'an.
Since Li Shimin created the killer foot force to seize power, the tang royal family's sons have effectively imitated, typical of his eldest son Li Chengqian, and then involved Li Tai, in the case of no crown prince in the country, Li Shimin can only let his youngest son Li Zhi take the throne, and then everyone must also know that he will take the Wu clan back to the palace, and then die of illness, the entire court is ruled by Wu Hou alone, and Li Dan is one of the sons of Wu Hou, he has twice become emperor, the last time he can take the throne, or the reason for his son Li Longji. At that time, he united with his aunt Princess Taiping, and the two of them teamed up to launch the Tanglong coup d'état, in which wei hou and Princess Anle were killed, and Li Dan was only forty-eight years old. This age is still in the prime of life for an emperor, after all, Liu Bang was already more than fifty years old when he ascended the throne.
So why did Li Dan, who was not very old and healthy, be emperor for only two years, and give up the throne that many people dreamed of to his son Li Longji? Moreover, it should be known that Li Longji is not his eldest son, Li Chengqi is the first candidate for the crown prince, in fact, it is reasonable to think about it carefully, because Li Longji played a key role in the coup d'état, it can be said that if there is no him in it, Li Dan's throne is still unknown, and at the same time, Li Chengji, as the eldest son of the concubine, is also a knowledgeable person, he knows that he is not as good as this younger brother, so he pushes the boat along the water and gives the position of prince to Li Longji, which is unexpected, but it is reasonable.
Logically, Li Longji has become the crown prince, as long as there is no rebellion, after a hundred years of Li Dan, the throne must be his, and the reason why Li Dan "retired" early is related to a woman, who is the Princess Taiping. As the youngest daughter of Empress Wu, Princess Taiping grew up in the imperial palace since childhood, and her parents loved her very much, originally married Xue Shao as a wife, but unexpectedly her husband was involved in the treason case, and was eventually imprisoned by Empress Wu and starved to death. It was also from then on that Princess Taiping began to contact power, and she was also one of the initiators of the Tang Long coup.
After the coup d'état, Li Dan was put to power, but there were three forces in the court, the first of which was the princeling party headed by Li Longji, followed by princess Taiping's henchmen, and a small number of loyal imperial parties, the later princess Taiping's desire for power, just like when Emperor Gaozong was just born, she was bent on emulating her mother's route of female emperor, Li Dan was also a cowardly emperor, but she also had a bigger opponent, that is, Li Longji, who used to cooperate together, for this nephew, Princess Taiping was disgusted more than liked, But she also had to admit his wisdom, the two people at first only fought in secret, and then became more and more intense, directly attacking each other in the court.
But to say which is the most uncomfortable, it is Li Dan sitting on the throne, one is his own sister, the two have a very deep relationship since childhood, the other is his own son, is the future heir of the Tang Dynasty, no matter which one prevails, Li Dan is not happy. Princess Taiping often preceded Li Dan, saying that she wanted to prevent Li Longji from emulating Emperor Taizong's actions in order to overthrow Li Longji and set up a cowardly prince to come to power, manipulating himself behind his back to achieve his own goals. Although Li Dan was cowardly, he was not a fool, and naturally understood Princess Taiping's thoughts, and as an old and good man, he could only persuade at both ends, or simply pretend to be deaf and dumb and did not respond.
However, this method did not last long, the party strife in the court became more and more serious, almost to the point of non-coexistence, Li Dan, under the balance, chose to give up the throne to his son who was more heroic than himself at the age of fifty, and directly announced the defeat of Princess Taiping. After Li Longji succeeded to his father's throne, he first swept away princess Taiping's henchmen, and then issued an edict to kill princess Taiping, and from then on, another era began in the Tang Dynasty. To sum up, it is not difficult to see that the reason why Li Dan chose to give way to his son in his prime was because there was a Princess Taiping in the middle, in order to maintain the stability of Jiangshan, there was no longer a matter of female state affairs, Li Dan had to give way and leave some good reputation for himself, if Li Tangjiangshan, who was not easy to restore, died at his own hands, then he really became a sinner of Li Tang.
In Li Dan's life, there were not too many meritorious deeds that could be left in history, and the upper could not open up the territory and expand the territory, nor did it create a prosperous world, but in the face of the supreme power, this rationality of retiring and not coveting power can be said to be rare in ancient times, and the rui character in Li Dan's temple number can be said to be just right. As soon as he gave the throne to his mother, although he was forced by the situation of the puppet emperor at that time, this decisiveness was really admirable. During the reign of Wu Zetian, the reign of Shangcheng Zhenguan and the prosperous era of The Lower Kaiyuan Can be said to have raised the comprehensive national strength of the Tang Empire to a new height, which is known in history as the "Legacy of Zhenguan".
Then he gave the throne to the crown prince Li Longji, one can stop the internal friction, and the second is that Li Longji's wenzhi martial arts are indeed much stronger than Li Dan's, and he has the appearance of a Ming Jun. Therefore, although Li Dan, who was no longer the puppet emperor who really held power, did not covet the throne in the face of the loss and recovery, the second emperor was located in the crown prince Li Longji, and the Tang Dynasty also reached its peak in the hands of Li Longji.
From this point of view, Li Dan's abdication of the throne at that time was so wise.
Note: The Zhenguan Relic is also known as the Reign of Xiao Zhenguan, and the Zizhi Tongjian believes that the reign of Emperor Gaozong of Tang Gaozong Li Zhi's Yonghui zhi has the Zhenguan Relic, while famous scholars believe that there was a Zhenguan Relic during the reign of Wu Zetian.