Tang Taizong has always been regarded by historians as the prince of the Holy Ming, and he worked hard to rule and create a prosperous situation of "the rule of Zhenguan".
However, his sons do not seem to have inherited his good genes, and many of his sons are not good, especially his eldest son Li Chengqian. He was young and intelligent, deeply loved by Emperor Taizong, and was made crown prince at the age of eight, but 17 years later, he was deposed for rebellion, and a good hand was played poorly.
Then, why did Li Chengqian, who was already the crown prince, risk rebellion?
As for the reasons for Li Chengqian's dethronement, historians of all generations have long studied it. The Old Book of Tang says, "The Father cannot move the foolishness of the Dead." He pointed out that the cause of Li Chengqian's tragedy was caused by his personal stupidity and stubbornness, and most people later accepted this view, believing that Li Chengqian's rebellion was abolished as a result of his own fault. The British scholar Howard Wechsler believed that "as he grew older, chengqian's behavior seemed abnormal and unorthodox in some respects to Chinese court officials; he may have been mentally disturbed." However, these views are biased, and the main reason for Li Chengqian's personal tragedy, in addition to Tang Taizong's mistakes in his education, is his failure in the party struggle in the early years of Zhenguan.
In fact, Li Chengqian was not a stupid person, on the contrary, he was eight years old at the time, intelligent and sensitive, and loved by Emperor Taizong. ''Tang Taizong commented on him'' "King Chengqian of Zhongshan, The Chief of the Land, Feng zi Junling, Ren Xiao Chun Shen, Ye Zhao Mao, Early Wen Ruizhe ... Ke Li Chengqian was made crown prince. As the eldest son of a concubine, Li Chengqian also had many excellent moral qualities, and was very fond of Emperor Taizong, and he was made crown prince very early, and Tang Taizong also cultivated and educated him.
First of all, it was to select famous teachers for him, and in July of the fourth year of Zhenguan (630), he selected the former imperial chancellor Li Gang as the prince's young master, the imperial master Xiao Yu as the prince's young master, and the famous Confucian Kong Yingda as the prince's right son, and Li Chengqian also had great respect for his teachers, and the master and apprentice got along very well. Secondly, it was the cultivation of his political ability, and in May of the fourth year of Zhenguan (630), when Li Chengqian was twelve years old, Emperor Taizong of Tang issued an edict: "From now on, those who have been judged by Shangshu Province have been judged by Shangshu Province, and have listened to the Eastern Palace Shangqi and appointed the crown prince to make a ruling. If you still don't accept it, then smell it. That is, Li Chengqian began to listen to lawsuits, intending to cultivate his administrative ability, and Li Chengqian's performance also satisfied Tang Taizong, until the death of Tang Gaozu Li Yuan in the ninth year of Zhenguan (635), Tang Taizong was positive about the crown prince.
During this period, Li Chengqian also had faults, he grew older, and his playful nature began to be exposed, "Good voice, roaming without moderation", but Emperor Taizong believed that it was harmless and could be corrected through education.
However, from the tenth year of Zhenguan (636), Emperor Taizong's attitude toward Li Chengqian began to change, the crown prince Chengqian himself suffered from foot diseases and walked with difficulty, the reputation of Li Tai, the king of Wei at that time, rose, and Emperor Taizong began to favor Li Tai, and Li Tai, relying on Emperor Taizong's favor and his own advantages, began to secretly cultivate his own forces, and at this time, the relationship between Li Chengqian and Emperor Taizong also began to deteriorate, and Emperor Taizong's suspicion of him became deeper and deeper.
Such a change is inseparable from Li Chengqian's character performance and Taizong's education, Li Chengqian's lameness and inability to move, his own personality is relatively inferior, Taizong's favor for Li Tai, and the killing of his favorite Tai Chang Le tong to praise the heart, and other practices have undoubtedly had an impact on Li Chengqian.
In order to encourage them to advise, Emperor Taizong also rewarded the ministers who advised him, and for a long time they could not be affirmed, and the psychological impact on Li Chengqian could be imagined, so that his behavior became more and more obedient, and later for the meritorious people who dared to put forward sharp opinions, "often sent people to plot and harm them."
With the increasing favor of Li Tai the Prince of Wei and the expansion of his power, in order to maintain his position as crown prince, Li Chengqian could not sit still and began to conspire with Li Yuanchang, the King of Han, Marquis Junji of Bingbu Shangshu, and others to attack the Western Palace.
In the seventeenth year of Zhenguan (643), when Li You, the King of Qi, rebelled in Qi Prefecture, Li Chengqian said to his defender Qigan Chengji: 'The western wall of my Eastern Palace is only twenty steps away from Ouchi, how can the King of Qi be compared?' Subsequently, when the rebellion of King Qi was implicated, and when he was arrested and imprisoned, he denounced the incident, and Li Chengqian was demoted to a commoner and exiled to Qianzhou, where he died in the nineteenth year of Zhenguan, after which Emperor Taizong stopped the imperial meeting for him and buried him with the ceremony of the Duke of Guo.
Li Chengqian originally wanted to get rid of his rival Li Tai in the form of a military coup, but he did not expect that the matter would leak out, and his position as crown prince could not be saved, and although Li Tai, the king of Wei, was deeply favored by Emperor Taizong, he could not ascend to the position of prince in the end, but li Zhi, the king of Jin, seemed to pick up the leak and ascended to the position of prince.