What is the truth about the Xuanwumen Change? Was it a ** carefully planned by Li Shimin, or was it a hasty counterattack under Li Jiancheng's step-by-step pressing, such a big thing happened in the palace, why did Li Yuan, as the emperor, not intervene, but like a puppet, give up the throne? This earth-shattering change started 6 years ago. In the third year of Wude in the Tang Dynasty, Li Shimin led his troops to attack Wang Shichong in Luoyang, Wang Shichong couldn't beat him, so he asked Dou Jiande for help, Dou Jiande was also very righteous, and brought 100,000 people to help the field, but he helped himself, and he and Wang Shichong both became Li Shimin's prisoners. Since the army in Taiyuan, Li Shimin has been rushing to the front line, fighting countless tough battles, he has long been the commander of the three armies, and now he has made such a great contribution, Li Yuan really doesn't know how to reward him, so he created a new official position, General Tiance. The status is above the three princes, below the crown prince, in fact, it is the third in command of the Tang Dynasty. 
In the following years, Li Shimin had more and more official positions on his head, and the power in his hands was getting bigger and bigger. Among them, the best one is this Tiance general. According to Li Yuan's regulations, General Tiance has the power to "open the government", what does it mean? You can appoint civil and military ** by yourself and establish a small court of your own. Originally, Li Shimin had many civil and military generals under him, and now they are even more like fish in water, and for a while, this Tiance Mansion has become the second power center of the Tang Dynasty. Li Shimin made such a high-profile appearance, which made one person very unhappy, and this person was the crown prince Li Jiancheng. It is said that this prince is the second-in-command of the Tang Dynasty, and only the prince has the power to open the government, recruit civil and military ministers, form his own team, and prepare for the future. However, the birth of Tiance Mansion has robbed the light that originally belonged to Li Jiancheng, and even the Prince's Mansion has been trampled under his feet. This is "take the prince's way, so that the prince has no way out". This kind of thing, resting on you, can you bear it? Of course, he couldn't bear it, so Li Jiancheng had to fight back. However, at this time, the relationship between the two of them has not yet reached the point of life and death, and Li Jiancheng's counterattack is only limited to the struggle for power. For Li Jiancheng, his advantage is that he has the identity of the crown prince, the support of the Long Group, and a group of ministers who help him with advice, such as Wang Qi, Pei Ju, and Wei Zheng; His disadvantage is that he doesn't have much military merit on his body, not that Li Jiancheng can't fight, but the identity of the crown prince determines that he has to stand at a higher level, to learn the art of the emperor, the strategy of governing the country, and the rough work of fighting is all thrown to Li Shimin. Therefore, Li Jiancheng decided to win back a game on the battlefield and take the initiative to take command to fight Liu Heimin. Liu Heimin was born in Wagangzhai, first with Li Mi, and then with Dou Jiande, in the fourth year after the establishment of the Tang Dynasty, he was beaten by Li Shimin and ran to the Turks. However, the Turks came out to work, working for a day's wages, and no one would really work hard, so after fighting, there were fewer and fewer people under Liu Heimin, and in the end, there were only more than 100 people left, and Li Jiancheng took them in one fell swoop. 
In the sixth year of Wude, the Turkic Jieli Khan attacked Shuozhou, which was another opportunity to make meritorious contributions on the battlefield, Li Jiancheng and Li Shimin, no one wanted to let go, so Li Yuan asked them to go to Bingzhou together to defend. Then the question arises, who will be the main general? In terms of identity, Li Jiancheng is the eldest brother, the crown prince, in terms of ability, Li Shimin's veteran driver on the battlefield, no one is willing to be the second one, so when they merged the state, the two estimated that there was a lot of friction, so in the eighth year of Wude, when the Turks attacked Dingzhou again, Li Yuan separated the two of them, let Li Jiancheng go to defend Youzhou, and let Li Shimin guard the state. Judging from this personnel arrangement, Li Yuan is balancing, playing with power, and letting the boss and the second fight each other, and he sits firmly in Diaoyutai. At the same time, from the perspective of an old father, he also doesn't want to treat anyone badly, after all, the palms and backs of his hands are all meat, and they are all his own sons, and it is difficult for him. Li Yuan's unsalty and indifferent attitude sent a wrong signal to Li Jiancheng, his position as the crown prince is not so solid, and there are fewer examples of the prince being deposed in history? Don't talk about it from afar, let's just say that the Sui Dynasty they just overthrown, who is Yang Jian's earliest prince, is the boss Yang Yong. That Yang Yong is also a talent, following Yang Jian's expedition to the east and west, the official worships the great Sima, the general, the Shangzhu country, the position of the prince is more stable than Li Jiancheng, and in the end he was not framed by Yang Guang and became a abolished prince. Therefore, Li Jiancheng played two cards. The first card, buy the harem. After the establishment of the Tang Dynasty, Li Yuan began to enjoy life, and there were many concubines around him, all of whom were young and beautiful, among which the most favored were Zhang Jieyu and Concubine Yin De, Li Jiancheng spent a lot of money on these people, and let them blow the wind on Li Yuan's pillow and say bad things about Li Shimin. If you take people's money, you have to do things for others, this Zhang Jieyu is also very smart, he knows that Li Yuan may not believe it if he says bad things with red lips and white teeth, but will cause a fuss for himself, so she thought of a way to take the initiative to provoke the contradiction between Li Yuan and Li Shimin. Li Shimin had a cousin named Li Shentong, who followed Li Yuan to raise troops, and he made a lot of contributions before and after the saddle, so Li Shimin gave him hundreds of acres of land in the name of King Qin. After Zhang Jieyu found out, she went to Li Yuan to be coquettish, and wanted to give those lands to her old father. Li Yuan didn't know it, so he happily issued an edict and gave these lands to his father-in-law. Now, the local ** is in a dilemma, on the one hand, there is the "fatwa" of the king of Qin, and on the other hand, the "edict" of the "emperor", what should I do? According to our current thinking, it must be carried out according to the emperor's orders. However, it was different at that time, Li Shimin was also a scholar and a magistrate, and his orders also had legal effect, so the following ** all had a common tacit understanding, that is, whoever received the order first, it would be executed according to whom. This time, they also gave the land to Li Shentong in accordance with this unspoken rule. At this time, Zhang Jieyu's goal was achieved, he ran to Li Yuan and cried, Li Yuan comforted for a long time to understand the cause and effect of the matter, and he was angry and called Li Shimin over and scolded: "You have a long ability, your words are more effective than my words." Seeing Zhang Jieyu crying next to her without crying, Li Shimin understood that he was put on the spot. The second card: Recruit soldiers and horses, whether it is the prince or the king of Qin, the soldiers under their command are all soldiers of the Tang Dynasty, and without Li Yuan's nod, none of them can be transferred privately. The only thing they could use was the guards around them, but the number was very limited. Li Shimin's Tiance Mansion has more than 200 guards and more than 50 military generals, and these generals have raised some private soldiers, adding up to more than 800 people. Of course, this is on the surface, secretly, Li Shimin also got more than 1,000 people, all of whom are strong in martial arts, and they are usually scattered among the people, and they can be assembled just by waiting for King Qin's order. 
Others don't know about these things, and it is impossible for Li Jiancheng not to know, so he also began to recruit soldiers and horses, but unlike Li Shimin, he did not hide these soldiers, but openly placed them in the prince's mansion in the name of strengthening the guards of the East Palace. Of these, 2,000 were infantry and 300 were cavalry. Li Jiancheng did this, Li Yuan may not know, but he just turned a blind eye, as long as it was not too much, he didn't bother to care. However, Li Shimin saw an opportunity from this, a good opportunity for the Jedi to fight back, so he made a decisive move.