Wu Zetian, as the only female emperor in Chinese history, left too many secrets after her death, such as the sudden violent death of the eldest son Li Hong, such as the rebellion and forced suicide of the second son Zhanghuai Prince Li Xian, such as the sudden death of the eldest daughter Princess Andingsi, which is still a secret even today, and there are many opinions.

In 651, Wu Zetian was taken into the imperial palace by Li Zhi from Ganye Temple, and became Zhaoyi, and from 652 onwards, Wu Zetian gave birth to four sons and two daughters for Li Zhi: Li Hong, Princess Andingsi, Li Xian, Li Xian, Li Dan, and Princess Taiping.
The birth of the eldest son, Li Hong, brought hope to Wu Zetian, and it should be known that before Li Hong, although Li Zhi already had four sons, they were all shuzi, and Empress Wang did not have children, and the crown prince Li Zhong was Li Zhi's eldest son. Li Hong's birth reawakened Wu Zetian's ambitions, others can be empresses, she can also, her advantage is Li Zhi's favor and son Li Hong. Therefore, in the next few palace fights, it is all around a theme, that is, Wu Zetian wants to be an empress. However, her biggest obstacle was that Empress Wang was born without any fault, and Empress Wang was supported by the powerful people in the dynasty, so Wu Zetian was very troubled, and although Li Zhi was biased towards Wu Zetian, he had never had the idea of deposing Empress Wang. In 654, the birth of Princess Andingsi gave Wu Zetian the tools to overthrow Empress Wang, and while Princess Andingsi was still in her infancy, she suddenly died mysteriously after Empress Wang visited her.
Empress Wang became the biggest suspect, and Li Zhi also believed that It was Empress Wang who did it, so Li Zhi finally moved the mind of deposing Empress Wang. In 655, Wu Zetian succeeded in becoming empress, and in this year, she also gave birth to her second son, Li Xian. The following year, Li Zhong was deposed and the five-year-old Li Hong became crown prince.
With the strong genes of Li Zhi and Wu Zetian, Li Hong is very good, benevolent and talented, has a strong learning ability, treats people and things in line with the identity of the prince, and as he grows up, especially after he begins to supervise the country, he performs very well, and his ability to handle government affairs is unanimously recognized by the courtiers, and most importantly, Li Hong can sympathize with the people's feelings, is very kind, he will even intercede for Xiao Shufei's two daughters (Li Hong's two half-sisters), to know that Xiao Shufei and Wu Zetian are considered to be sworn enemies. Whether this move provoked Wu Zetian or not, we do not know. Many people suspected that Wu Zetian was not satisfied with this son because of this incident, so they finally got rid of him, but the fourth girl felt that Li Hong's death had nothing to do with Wu Zetian, on the contrary, Li Hong's death, Wu Zetian was very sad.
In fact, Li Hong has been frail and sick since he was a child, and when he was supervising the country in the later period, many things were handed over to the people below, and his own body obviously could not withstand excessive fatigue. In 675, Li Hong traveled with Li Zhi and Wu Zetian to Luoyang, where he was completely devastated and died suddenly at the age of 24 in the Qiyun Hall of the Hebi Palace.
After Li Hong's death, Li Zhi also made his second son Li Xian the crown prince, Li Xian's talent was not inferior to Li Hong,Or even superior, he was able to summon scholars to annotate the Book of Later Han is a good example, Li Xian was liked by Li Zhi from a young age because of his intelligence and handsomeness, after becoming a prince, he was also knowledgeable, and his political ability when he supervised the country was good, and he was also praised by the courtiers, but Li Xian had a contradiction with his mother Wu Zetian, and Wu Zetian was not satisfied with this son. Perhaps the reason is that Wu Zetian's increasingly inflated desire for power, so Wu Zetian will beat and rebuke Li Xian from time to time, which makes Li Xian breed fear in his heart, and Li Xian's life seems to have some unknown secrets, some people say that Li Xian is not Wu Zetian's son, but Wu Zetian's sister and Li Zhi's son, which also makes the mother and son out of their hearts.
At that time, the warlock Ming Chongyu was very favored by Wu Zetian, and Ming Chongyu once told Wu Zetian that Li Xian and Li Dan were more suitable to be princes than Li Xian, and Li Xian also disliked Ming Chongyu. In 679, Ming Chongyu was suddenly killed by a gang of robbers, Wu Zetian suspected that it was Li Xian's hand, so in the following year, Wu Zetian had people accuse Li Xian of plotting rebellion, and the evidence of rebellion was very sufficient, but Li Zhi was not willing to punish Li Xian, but Wu Zetian demanded that Dayi exterminate his relatives, and eventually Li Xian was deposed as a Shuren, put under house arrest, and three years later, exiled to Bazhou.
Soon, Li Zhi died, and soon, Wu Zetian controlled the government, Emperor Zhongzong Li Xian was deposed as the king of Luling and exiled, and Ruizong was placed under house arrest, while Wu Zetian was still uneasy about Li Xian, who was far away in Bazhou, and specially sent Qiu Shenxun to Bazhou to monitor Li Xian, but after Qiu Shenxun arrived in Bazhou, he directly forced Li Xian to commit suicide, and the 30-year-old Li Xian completed his tragic life.