Li Yuan had many children, of whom there were twenty-two sons, and the ones he attached the most importance to were the children born to the original Empress Dou, that is, Li Jiancheng, Li Shimin, Li Xuanba, and Li Yuanji. Li Xuanba died young, so the candidate for the throne was chosen among the other three, and Li Jiancheng, the eldest son, naturally became the most righteous heir. Li Shimin, who had the strongest ability and the highest military achievements, has always threatened Li Jiancheng's position, so the brothers continued to fight, and eventually evolved into the change of Xuanwumen. Since then, Li Yuan abdicated and Li Shimin officially ascended the throne, creating the later Tang Dynasty.
From Li Yuan's various behaviors, it can be seen that the most optimistic successor in his heart has always been Li Jiancheng, and although this eldest son has a poor ability to lead troops, he has always behaved very decently in front of his old father, coaxing Li Yuan to be very happy, and he is also more and more fond of Li Jiancheng. Compared with Li Jiancheng's comfortable life as a prince, Li Shimin worked much harder, and has been fighting outside, making great achievements for the Tang Dynasty. At the same time, perennial conquest also allowed Li Shimin to grasp most of the military power, which gave him a very high reputation. Li Jiancheng realized that Li Shimin's growth would threaten his position, and had been secretly fighting with him, didn't Li Yuan know this? Of course, Li Yuan also knew it, so why not limit Li Shimin's power?
In fact, it is not that Li Yuan does not restrict Li Shimin, but that he is also powerless. Although he recognized Li Jiancheng more as his successor and tried his best to cultivate him, the development of the situation was often out of his control. At the beginning of the establishment of the Tang Dynasty, Li Jiancheng, Li Shimin and Li Yuanji all held military power and fought for Li Yuan everywhere before laying the foundation of the country. Moreover, as the crown prince, Li Jiancheng had the largest number of troops, after all, the safety of the heirs was very important. At first, Li Shimin only had eight hundred elite soldiers, and the later growth was completely his own.
It can be seen from this that Li Yuan did not allow Li Shimin to grow, but divided the military power among his three sons, and Li Shimin was the one with the least military strength, and Li Yuan was actually suppressing Li Shimin from the beginning, so that he would not surpass the prince. However, with the changes in the situation, Li Jiancheng's ability to lead troops to fight became more and more stretched, and the number and strength of his army were constantly decreasing. On the other hand, Li Shimin, with his super military ability, created a vast world for himself, not only expanded his army and enhanced his military power, but also won himself a good reputation in the army. It is no wonder that Li Yuan, who let Li Jiancheng's ability to be limited, so quickly compared to Li Shimin.
Seeing that Li Shimin was constantly becoming stronger, Li Yuan did not sit idly by, but repeatedly wanted to limit Li Shimin's military power. The first time was when Wang Shichong was defeated, and Li Shimin originally wanted to continue to the south and sweep away the remnants of his forces, but Li Yuan refused. On the surface, he was rewarded, but behind the scenes, his military post was suspended, so that Liu Heimin was given a chance to breathe and constantly confronted the Tang. Li Yuan sent a number of generals to suppress the rebellion, and there was no return, and in the end there was really no way out, seeing that the safety of The Tang Dynasty was threatened, he agreed to let Li Shimin go to quell the rebellion. As soon as Li Shimin left, he solved Liu Heimin, and Li Yuan repented that he was not at the beginning, originally to restrict him, but he did not expect to make his prestige even greater in the end.
The second time was when the Turks invaded the tang border, Li Yuan refused Li Shimin's participation in the war, but transferred Li Shimin's generals to Li Yuanji and asked him to quell the rebellion, hoping to use this to break down Li Shimin's power. Li Yuan's restrictions on Li Shimin did not end there, and later he constantly dismissed the generals around Li Shimin, either to other armies or to local posts. However, these moves not only did not weaken Li Shimin's power, but on the contrary, they aggravated the contradictions between him and Li Jiancheng, making him finally intolerable.
In the end, Li Shimin had to launch the Xuanwumen Rebellion to protect his rights and interests, and even though most of his power was restricted, Li Shimin easily defeated Li Jiancheng, which made Li Yuan no longer have the ability and excuse to restrict Li Shimin. In the face of the situation of fratricide, Li Yuan can only choose to abdicate, after all, he and Li Shimin are no longer the harmonious father-son relationship as before, and it is only a matter of time before Li Shimin ascends the throne. Ignoring the change of Xuanwu Gate, Li Shimin's reputation in history is very good, he is one of the most outstanding emperors, and he has always been admired by future generations, which is enough to make Li Yuan feel pleased!