In 624 AD, Li Yuan had already sat on the throne for the 7th year, the Tang Dynasty basically unified the country, the society returned to stability, Li Yuan, who was not very fond of handling government affairs, often let the crown prince Li Jianjian supervise the country and play everywhere by himself. This summer, the weather was very hot, Li Yuan could not bear it, so he ran outside Chang'an City to escape the summer, Li Shimin and Li Yuanji followed, and Li Jiancheng stayed behind in the Beijing Division.
However, just when Li Yuan was in a good mood, a secret report suddenly came, saying that Yang Wengan, the governor of Gyeongju, intended to rebel. Gyeongju's location is probably in the southeast of today's Gansu and the south of Ningxia, very close to Chang'an, and if there is a real rebellion, then the Li-Tang Dynasty will face a huge crisis.
However, Yang Wengan was a close confidant of Li Jiancheng, and he did not plot rebellion early or late, but chose to rebel when Li Yuan left the capital, which is difficult not to conclude that Li Jiancheng colluded with Yang Wengan and planned to ascend the throne in advance. Li Yuan also thought so, and he was not in the mood for a vacation, but in order not to fight the grass and snake, he sent someone to lie that there were other things to discuss with the prince, so that Li Jiancheng would immediately come to see him.
After all, Li Jiancheng was the crown prince, and he also had a large number of intelligence personnel under him, so he already knew about Yang Wengan's rebellion, and he also knew very well why Li Yuan had asked him to go. Li Jiancheng's personality was indecisive, and he was even more overwhelmed when he encountered this kind of thing, and there were two roads in front of him at that time: 1. Simply go out, directly rebel, and Cooperate with Yang Wengan, the general situation in the world is unknown; 2, obediently obey, take the initiative to ask Li Yuan for guilt, and find a way to clear his suspicion of conspiracy and agitation.
Li Jiancheng did not have the courage to rebel, and finally chose the second way, he fell to the ground and cried after seeing Li Yuan, always saying that this matter had nothing to do with him, and his emotions were too excited, so that he almost fainted. However, Li Yuan was angry and did not believe Li Jiancheng's defense at all, and immediately ordered him to be imprisoned.
After settling down on the internal "traitors," Li Yuan aimed the spearhead at the external "traitors," and he repeated his tricks and sent people to lie that there were other things to discuss, so that Yang Wen could see them. In fact, Li Yuan's methods were too naïve, Yang Wengan had already started a rebellion, was it so coincidental that the emperor summoned him at this time?
Therefore, as long as anyone with a little political acumen will not obey the order, not to mention that Yang Wengan has already learned about the dynamics of the capital through secret agents, and it is very clear that he has torn his face with Li Yuan, and it is a dead end to see that stubborn resistance may still have a glimmer of life. Therefore, Yang Wengan took advantage of the situation and prepared to lead his troops to Kill Chang'an.
At this point, Li Yuan could only send troops to suppress the rebellion, and this task soon fell to Li Shimin. We know that Li Shimin is the god of war of the Tang Dynasty, who has laid half of the country, and his military ability is beyond doubt. However, this expedition was somewhat different from the past, and before leaving, Li Yuan specially summoned Li Shimin and told him that he must seriously fight the war, and after quelling the rebellion, let him replace Li Jiancheng's position as crown prince.
Li Shimin had long been waiting for this day, and led his army out with excitement, but before the two sides could formally clash, Yang Wengan was killed by his subordinates, and the rebellion ceased to exist. After the triumph of the army, Li Shimin rushed to Li Yuan to ask for credit, waiting for his father to announce the decision to replace the crown prince.
However, Li Yuan only verbally praised a few words, and then acted as if nothing had happened. What made Li Shimin even more unexpected was that Li Jiancheng had actually been released and continued to handle state affairs as a prince. Immediately afterward, Li Yuan began to investigate the specific person responsible for Yang Wengan's rebellion, and instead of blaming Li Jiancheng, he believed that several staff members of the Eastern Palace and the Qin Dynasty Palace had instigated brothers to fight each other, which caused this farce.
Li Shimin's trusted aide Du Yan was exiled, many people may not be familiar with him, this person is talented, but good at engaging in conspiracy and trickery, and Chen Ping and Cao Wei Jia of the Han Dynasty are the same type of courtiers, and his son is the famous Tang Dynasty prime minister Du Ruyi. In Li Yuan's view, he also did this out of helplessness, Li Shimin had already made a great contribution to the lord, and there was no way to continue to award rewards, but because of his excessive power, he needed to suppress it.
Li Jiancheng is no good, after all, he is the eldest son of a concubine, and Li Yuan, who strictly abides by the patriarchal inheritance system, will never easily depose the prince, not to mention that after a detailed investigation, Yang Wengan's conspiracy against the prince is not directly related, Li Jiancheng just wants to send a batch of armor to Gyeongju to strengthen the armament, although it violates the system, but it has not yet reached the point of rebellion.
After thinking left and thinking about it, Li Yuan finally decided to fight fifty boards each, weakening Li Shimin's power on the one hand, and beating Li Jiancheng on the other hand. However, in Li Shimin's view, Li Yuan, as the emperor, was not trustworthy, neither a qualified ruler nor a loving father, but played his son as a monkey, and you can imagine how angry he was in his heart.
Through the clues of historical materials, posterity found that Yang Wengan's rebellion was most likely a ghost behind Li Shimin's back, because the person sent by Li Jiancheng to transport the armor was just touched by the people of the Qin Royal Palace, and it is difficult to say that this is just accidental. However, no matter who was behind the command, the relationship between Li Shimin and Li Yuan was completely broken after this incident, and he also made up his mind from then on, hoping that It would be impossible for Li Yuan to pass on the throne, and the only way to ascend to the throne of God was through force.