Among the many emperors of the Tang Dynasty, three received relatively high praise from people: Emperor Taizong, Emperor Xuanzong, and Emperor Xianzong. Emperor Taizong initiated the "Zhenguan Governance," and Emperor Xuanzong ushered in the "Kaiyuan Golden Age," both achieving remarkable accomplishments. Emperor Xianzong was able to be compared alongside these two outstanding emperors because his reign saw the "Yuanhe Restoration."
Emperor Xianzong of Tang, originally named Li Chun, changed his name to Li Chun after being appointed crown prince, and was the eldest son of Emperor Shunzong of Tang. Li Chun's grandfather was Emperor Dezong of Tang. When Li Chun was young, his grandfather once held him in his arms and teased him, saying, "How did you end up in my arms? Whose child are you?" Li Chun calmly replied, "I am the third Son of Heaven." Emperor Dezong was the emperor, the first Son of Heaven. As the eldest grandson, Li Chun was expected to inherit the throne, so he called himself the third Son of Heaven. His answer greatly surprised Emperor Dezong. From then on, Emperor Dezong grew even fonder of Li Chun and, when Li Chun was eleven, enfeoffed him as the Prince of Guangling.
In 805 AD, Li Chun ascended the throne at the age of twenty-eight, becoming Emperor Xianzong of the Tang Dynasty. Li Chun frequently read historical records, and whenever he came across accounts of how Emperor Taizong Li Shimin and Emperor Xuanzong Li Longji had created eras of great prosperity, he would become deeply inspired, regarding them as role models to emulate, hoping to achieve similarly great accomplishments.
Since the outbreak of the An Lushan Rebellion, the Tang Dynasty fell into a state of regional military governors' separatist rule. During the reign of Emperor Dezong of Tang, the military governors of various provinces in Hebei launched rebellions, bringing severe disasters upon the Tang Dynasty. After Emperor Xianzong of Tang ascended the throne, he was determined to implement a policy of reducing the power of these regional military governors, hoping to change the situation of separatist rule through this policy.
In 806 AD, Liu Pi, the military governor of Xichuan, launched a rebellion. Upon receiving the news, Emperor Xianzong of Tang immediately appointed Gao Chongwen as the military governor of the Left Shence Field Camp, commanding Li Yuanyi, the commander of the Shence Western Field Camp, and joining forces with Li Kang, the military governor of Jiannan Dongchuan, and Yan Li, the military governor of Shannan Xidao, to jointly suppress Liu Pi. Liu Pi's troops were relatively weak in combat effectiveness and were quickly defeated. Liu Pi was captured and later sent to Chang'an, where he was executed.
After the imperial court successfully suppressed Liu Pi's rebellion, the various military governors across the regions felt their positions were precarious. Li Qi, the military governor of Zhenhai, fearing the court would strip him of his military command, requested to serve as an official in the capital. Emperor Xianzong of Tang agreed to Li Qi's request, but when the time came to report to the capital, Li Qi claimed he was gravely ill and could not travel. Wu Yuanheng, the Vice Director of the Chancellery and Hanlin Academician who strongly advocated for reducing the power of the military governors, advised Emperor Xianzong that such defiance should not be tolerated and that the governors must be made to respect the court's authority. The emperor agreed wholeheartedly, so he appointed Li Qi as Right Vice Director of the Department of State Affairs, appointed Wang Dan as acting military governor, and appointed Li Yuansu, the Imperial Censor-in-Chief, as the prefect of Runzhou. Thus, Li Qi's military power was stripped away. Enraged and humiliated, Li Qi launched a rebellion in Runzhou, killing Wang Dan. Emperor Xianzong immediately mobilized troops from Yining, Xuanwu, Huainan, and other regions, appointing Wang E, the military governor of Huainan, as the Supreme Commander for Pacification and Suppression to lead the various armies in a joint campaign against Li Qi. Facing the massive imperial army sent to suppress him, Li Qi quickly suffered defeat and was sent to the capital, where he was executed.
In 812 AD, Tian Ji'an, the military governor of Weibo, passed away, and military affairs in Weibo were supposed to be handled by his son Tian Huaiqian. However, Tian Huaiqian was too young to manage military matters, so Tian Ji'an's household servant Jiang Shize and others seized control of Weibo's military power. Emperor Xianzong of Tang saw this as an excellent opportunity to weaken the feudal domains and planned to appoint Xue Ping, the Left Grand General of the Dragon Guard, as the military governor of Zheng and Wei to take control of Weibo. Prime Minister Li Jiang argued that the morale of Weibo's troops was unstable and that internal conflicts within Weibo could be exploited to bring it back under imperial control. Emperor Xianzong agreed this was a good strategy and decided to proceed accordingly. The soldiers and officers of Weibo jointly recommended Tian Xing, a general under Tian Ji'an, to lead Weibo's military. Tian Xing led the troops to kill Jiang Shize and others, and sent Tian Huaiqian to the imperial court. Emperor Xianzong issued an edict appointing Tian Xing as the military governor of Weibo. Grateful for the emperor's favor, Tian Xing submitted to the imperial court. Emperor Xianzong was delighted, rewarded the soldiers of Weibo, and announced a one-year tax exemption for the people of Weibo's six prefectures, bringing great joy to both the soldiers and the people. Thus, Emperor Xianzong successfully reclaimed the six prefectures of Weibo.
In 814 AD, Wu Shaoyang, the military governor of Huaixi, died, and his son Wu Yuanji seized control of the Huaixi army, occupying three prefectures around Caizhou and launching a rebellion. Although Caizhou was not large in area, it was close to the eastern capital Luoyang, making its strategic position highly important. Therefore, Emperor Xianzong of the Tang Dynasty decided to recover Huaixi.
After hearing about this, Li Shidao, the military governor of Ziqing, feared that the imperial court might take action against him, so he secretly supported Wu Yuanji. He sent men to Heyang (north of present-day Xingyang, Henan) to burn all the grain and property collected by the court from the Jianghuai region; he also sent men to the capital Chang'an to assassinate Prime Minister Wu Yuanheng, who strongly advocated for a military campaign against Huaixi.
Li Shidao did this to force Emperor Xianzong of Tang to stop the military campaign against Huaixi. However, Emperor Xianzong was very determined to recover Huaixi. He appointed Pei Du as the military governor of Zhangyi and Li Su, the chief steward of the crown prince, as the military governor of Tang and Deng, leading a large army to attack Wu Yuanji. Li Su launched a surprise night attack on Caizhou, captured Wu Yuanji, and thus ended the rebellion in Huaixi.
After Wu Yuanji died, Li Shidao launched a rebellion. Emperor Xianzong of the Tang Dynasty mobilized troops from Weibo, Wuning, Xuanwu, and Henghai to suppress Li Shidao. Facing the powerful imperial army, internal conflicts arose within Li Shidao's camp, and he was killed by his own subordinates. As a result, Emperor Xianzong regained control of Qing, Zi, and Jiangzhou regions.
After suppressing the rebellion led by Li Shidao, the Tang Dynasty's territory was temporarily unified, and Emperor Xianzong's policy of reducing vassal power achieved great success.
In addition to reducing the power of regional governors, Emperor Xianzong of Tang also appointed a group of capable and virtuous individuals as chancellors. Through their joint efforts, the government's financial situation improved, national strength was enhanced, and the Tang Dynasty experienced a period of revival.
Because these events occurred during the Yuanhe era of Emperor Xianzong of Tang, this period is called the "Yuanhe Restoration."