As we all know, Li Shimin is Li Yuan's concubine, but not the eldest son. Originally, the throne could not be turned by him, but Li Shimin launched the Xuanwumen Revolution and snatched the throne from his father and brother.
And Li Shimin has a son, it can be said that Li Shimin's history is extremely admired, and he also wants to emulate it once, and this stupid son is Li You.
Let's take a look at Li You's identity first. His mother was the Yin clan, whose name is not recorded in the history books, and the father of the Yin clan was the Yin Shishi, who was finally killed by Li Yuan because of his vendetta against Li Yuan. After Yin Shishi was killed, his daughter Yin Shi was assigned to Li Shimin as a concubine by Li Yuan.

Originally a prisoner, he later became Li Shimin's concubine, and after Li Shimin ascended the throne, the Yin clan also became a lady, second only to the empress. To be able to have such a status, it is because the Yin clan has given birth to a son, the mother is gui, and this son is Li You.
Now we can know that Li You is not a concubine. Li Shimin had three concubines: Li Chengqian, Li Tai, and Li Zhi, the first three heirs of the throne, followed by Li Ke, the eldest son of Shu, and then Li You, the second son of Shu. According to the Tang Dynasty's rule of "standing up for a concubine and not standing for a long time, and standing tall is not a young person", Li You is only counted as the fifth heir to the throne, and it can be said that he cannot be turned in any way.
In fact, such an identity is also very good, as long as you are not greedy, honestly be an idle prince, and have no worries about food and clothing for a lifetime. Live well in your own fiefdom, and your life can be very good, after all, the Tang Dynasty was in its heyday at that time.
However, Li You did not think so, he thought that although he was not a concubine, he was also the son of the emperor. Father Li Shimin, who did not take the throne as the eldest son of a concubine, why didn't he emulate his father and make a change in Xuanwumen.
The idea was quite good, but Li You seemed to be a little confused about himself. His fiefdom was Qi Prefecture, which was "108,000 miles" away from Chang'an, but Li You himself was very confident and believed that with his own ability, he would be able to fight from Qi Prefecture to Chang'an, so he decided to start an army from Qi Prefecture.
But what if QiZhou's troops are insufficient? There was a man who advised him, and he was Yin Hongzhi. Yin Hongzhi is the older brother of the Yin clan, that is, Li You's uncle. He had been encouraging Li You to rebel, and he himself wanted to avenge the death of his father. Where did Li You know about his uncle's plot, and he thought that his uncle felt that he had the ability to lead the country and had always fully supported him.
Yin Hongzhi advised Li You, saying: "You can raise the banner of rebellion, and when the people of Qi Prefecture hear about it, they will definitely rush to surrender, and when the time comes, they will gather a million male divisions, and He Shuo will not be able to fight Chang'an." Li Youxin believed it to be true, so he ordered the recruitment of soldiers.
Don't say anything about the million male masters, no one has signed up at all. What a wise emperor Tang Taizong was, and now that he was in a peaceful and prosperous world, who would still be willing to go to war? Some people even think that Li You's act of disloyalty, filial piety, and injustice is even considered, and who is willing to support him? There are only a few thousand people recruited.
Before the soldiers and horses arrived here, the news from that side reached Chang'an. When Li Shimin heard of his son's rebellion, he immediately sent Li Ji and Liu Dewei to arrest him. Li Ji was one of the Twenty-Four Meritorious Men of LingYange, along with Li Jing, the Duke of Weiguo. Liu Dewei was a veteran general who served the Tang Dynasty during the Li Yuan period, and he had experienced a hundred battles and made remarkable achievements.
Li You was well aware of the strength of the two generals, and for a moment he was at a loss, so he asked his uncle Yin Hongzhi what to do. At this time, a man named Yan Hongliang said to Li You, "The king does not have to worry! Hongliang and others hold the wine in their right hand, and the left hand swings the sword for the king! "This Yan Hongliang was introduced by Yin Hongzhi and was one of Li You's staff. What he meant by this was, don't worry, we drink wine with our right hand, and slash and kill the king with a knife in our left hand. When Li You heard this, his confidence came up again.
And Li Shimin on this side could not bear to hurt his son, so he wrote a letter to persuade his son to surrender, so that he could remember his family affection and not pursue him too much. In fact, at this time, if Li You woke up, even if he was relegated to a commoner in the back, he could at least save his life, and maybe when Li Shimin remembered his family affection, he would recall him. To put it bluntly, it is to leave a life and have hope.
However, Li You did not believe in evil and was determined to fight his father to the death. Li Shimin had to make up his mind to let Li You know what "your father is always your father."
Yin Hongzhi was crazy and Li You was stupid, but the soldiers in Qi Prefecture had no reason to accompany them crazy and stupid. Everyone heard that it was Li Ji and Li Dewei who came this time, and they knew that they were not opponents, so they all turned against each other and surrendered. In the end, qizhou's soldiers united and captured Li You alive and handed him over to Li Shimin.
At this time, Li You knew that he was afraid, and quickly wrote a letter to his father, saying that he knew that he was wrong, hoping that his father would think of family affection and not care about his ignorance. Unfortunately, it was too late, my father had already given him a chance, but he didn't know how to cherish it. After Li Shimin read the letter, he made three sacred decrees in succession:
I. Commend the soldiers and people of Qi Prefecture for not relying on the rebels at a critical moment, and exempt Qi Prefecture from paying taxes for one year.
2. Commend the soldiers who captured Li You alive and add officers to the knighthood.
3. Reduce Li You to a commoner and give him a cup of poisoned wine.
Therefore, it is not that Li Shimin disregarded his family affection and wanted to give his own son poisonous wine, but that this son was too stupid to see the facts clearly. But anyone with a little intelligence would not do such a thing, not Li Shimin gave death to his son, but Li You's success in "finding death".
On the contrary, Li Shimin also remembered his family affection, and after Li You's death, he was buried with the etiquette of the Duke of Guo. In this life, the emperor can't do it, or be a good prince below.
(References "New Book of Tang", "Old Book of Tang", "Zizhi Tongjian")