Since the Tang Dynasty went through those "Xuanwumen Changes", the emperors did not trust their sons at all; after the "Anshi Rebellion", these emperors no longer believed in those generals and generals. Therefore, in this context, the emperor can only trust one kind of person, that is, the most intimate person around him- the eunuch.
In quelling the Anshi Rebellion, in order to prevent the appearance of a second An LuShan, the emperors were full of suspicion of the generals who commanded the army, so much so that they preferred to trust the eunuchs who could not fight, rather than these fierce generals who could fight well. Therefore, in this context, the supervision of the military system came into being at this moment.

The so-called supervision army is a eunuch sent by the emperor to the war zone to inspect the combat situation. In addition, the emperor not only sent eunuchs to serve as supervisors, but also set up supervisors in the war zone, and even military units two or three levels smaller than the war zone also had to set up supervisors.
After the Anshi Rebellion, the armed forces of the Tang Dynasty had two "systems", one was the traditional military system, and the other was the eunuch system that could directly reach the emperor's throne. The task of the supervision army, ostensibly to help solve difficulties, is in fact to prevent mutiny from occurring. As soon as there were signs of rebellion in the war zone, the eunuchs of the supervising army could make the rebels' heads fall to the ground.
Preventing rebellion was the emperor's original intention of setting up the supervision army, but because the eunuchs in the supervision army were too powerful, when these people experienced the "benefits" of power, you wanted them to give up, and the result was imaginable.
If before Tang Dezong, eunuchs had only occasionally gained power, then by the time the emperor arrived, these eunuchs had become more and more uncontrollable.
At the beginning of Tang Dezong's succession, he adopted the basic principle of "approaching the courtiers and neglecting the eunuchs", but because in the days of hasty escape, these eunuchs have always followed him, supported him, protected him, never abandoned, and consistent, which is in stark contrast to those rebel military generals who come and go from side to side, which deeply affected Tang Dezong and completely changed his view of employing people.
In October of the first year of the Xingyuan Dynasty (784), Emperor Dezong of Tang issued a decree appointing the eunuchs Dou Wenchang and Wang Xiqian as the commanders of the Left and Right Divine Strategies Army, in charge of the world's soldiers and horses. It should be known that the so-called "Divine Strategy Army" was the final combination of the original Ten Thousand Horsemen Army and the Longwu Army, and was the most elite unit of the Tang Dynasty at that time, responsible for protecting the safety of the emperor.
Such a prominent official position, since ancient times, is not the emperor's relatives and relatives, the emperor's 100% trust, the result is that this group of eunuchs got it.
Of course, for Tang Dezong, "the wind knows the grass, and the board knows the sincere subjects", after this turmoil, he can only trust this group of people.
Tang Dezong did not expect that under his connivance, this group of eunuchs who had been entrusted with heavy responsibilities would change their appearance and become the people who ran the country and even manipulated the fate of the emperor.
In the first month of the twenty-first year of Zhenyuan (805), after countless sword and light sword shadows and power struggles, Tang Dezong Li Shi finally ushered in the final peace. It was in this quiet life that his life finally came to an end, at the age of sixty-four.
On the twenty-third day of the first month, after twenty-six years as crown prince, Li Xuan, who was already forty-five years old, ascended the throne as emperor, and was known as Tang Shunzong.
Because he had been the crown prince for twenty-six years, during this long period, Tang Shunzong Li Xuan witnessed the rebellion and fireworks in the town and the eunuchs, so as soon as he ascended the throne, he could not wait to carry out a reform, known in history as the "Yongzhen Reform".
In Chinese history, because this reform was initiated by Wang Ling and Wang Shuwen, it was also called the "Two Kings Reform". Later, when this reform failed, Wei Zhiyi, Han Tai, Chen Chen, Liu Zongyuan, Liu Yuxi, Han Ye, Ling Zhun, and Cheng Yi under the "Second King" were all demoted to the status of Sima of the Prefecture, so it was also known as the "Erwang Eight Sima Incident".
Whatever the name, in the history of the Tang Dynasty, this was a failed coup.
After the reform began, with the gradual introduction of policies such as the boycott of the five envoys of the palace city, the abolition of the entry of the provinces, and the severe punishment of corrupt officials and corrupt officials, the imperial court was indeed invigorated. The strength of the eunuchs was getting worse and worse, and the clan town also began to restrain its arrogance, so that all the people could see it in their eyes and rejoice in their hearts.
According to the historical records of the time, this "yongzhen innovation" that will forever go down in history is like dropping an atomic bomb that has changed the world and the earth in this smoky miasma and decadent society, which not only blows up corruption and harsh government, but also blows up a new world.
It took only two months to achieve such great political achievements, and if such reforms continue, in time, the Tang Dynasty will certainly be able to eliminate all the tumors and create a prosperous and prosperous world.
Unfortunately, in the dictionary of history, there is never the word "if".
As we all know, the so-called "reform" is, to put it bluntly, a comprehensive reshuffle of the country's political, military, and economic affairs, and a readjustment of the country's strength. However, in that era of family and world, for the reformers, the time of reform did not depend on the achievements of history, the needs of the people, etc., but in fact depended on two points:
First, the degree of support of the monarch; Second, the length of the monarch's life.
Obviously, on the first issue, Tang Shunzong was able to support it one hundred percent; But on the second question, he was powerless, or even powerless.
Due to his frail health and illness, and suffering from stroke and loss of voice, it was not long before Emperor Shun of Tang was seriously ill and could not go to the court, and all the affairs of the imperial court could only be entrusted to the eunuch Li Zhongyan and the most favored Niu Zhaoyi.
You know, for such two people who do not eat "human fireworks" at all, as long as the people do not rebel, everything can be ignored.
The achievements of the Yongzhen reform, which had been so hard to establish, were completely destroyed by them.
During the two men's reign, those whose interests were damaged immediately attacked the reformers. They accused Tang Shunzong of improper employment. Wang Huai, Wang Shuwen, and others who were entrusted with heavy responsibilities were all villains who had "brought calamity to the chaotic dynasty" and must be expelled from the country in order to return to the world for "peace."
Just as the so-called "house leaks in the overnight rain, the ship is late and the head is blowing", just when the reformists are being attacked by the old force groups one after another, taking care of themselves, and being anxious, Wang Shuwen has suffered another major blow, his father has died, and he is ordered to go back to DingYou for three years.
In China, filial piety is one of the highest moral codes for people, and the most basic social ethical code in traditional Chinese culture.
Wang Shuwen could only obediently announce his resignation and honestly went home to keep filial piety.
When Wang Shuwen, the core figure of the reformers, returned home, it was tantamount to announcing the failure of this reform. Seeing that the general trend had gone, another core figure, Wang Ling, spat out blood and fell ill. It wasn't long before the brother died mysteriously.
The two elders walked away and died, resulting in the leaderlessness of the reformers and chaos. Tang Shunzong was also powerless, but was pressed step by step by Li Zhongyan, Niu Zhaoyi and others, and finally signed a letter in a confused situation, announcing that the crown prince was supervising the country and that he was honestly the emperor.
Five months after the last "Xuanwumen Revolution" of the Tang Dynasty, Tang Shunzong, who had been the crown prince for twenty-six years and emperor for one year, died and drove to the west of hexi.
With his death, this "Eternal Zhen Innovation", which lasted for eight months and only reformed for a hundred days, was short-lived and completely ceased to exist.
There is no doubt that the "Yongzhen Reform" was the "best" opportunity for the Tang Dynasty to revive. Because from then on, neither the emperor nor the ministers could change this society and carry out another thorough reform.
The "Yongzhen Innovation", which lasted only more than two hundred days, became the most unforgettable pain in the life of the Tang Dynasty.