Loss of Chengde, Lulong, and Weibo Circuits
As soon as Emperor Muzong took the throne, he put to death the alchemists who had been supplying Emperor Xianzong with the immortality pills. He further quickly exiled the chancellors Huangfu Bo and Linghu Chu, replacing them with new chancellors. He also honored his mother Consort Guo as empress dowager and was extravagant in supplies to her. He himself was spending much time in games and hunts, against the advice of those officials who found such activities inappropriate, but was said to be tolerant toward those giving such advice.
At the time that Emperor Muzong took the throne, he inherited a state that had just recently been, during his father's reign (which was known as the Yuanhe Restoration (元和中興), due to Emperor Xianzong's era name's being Yuanhe), restored to unity under the imperial government after various circuits, the most defiant of which were Pinglu (平盧, headquartered in modern Tai'an, Shandong), Weibo (魏博, headquartered in modern Handan, Hebei), Chengde (成德, headquartered in modern Shijiazhuang, Hebei), and Lulong (盧龍, headquartered in modern Beijing), had been effectively independent from the imperial government. As of 819, when Emperor Xianzong's forces crushed those of Li Shidao, the military governor of Pinglu, in effect, these circuits that had broken away from the imperial government since the end of the Anshi Rebellion had resubmitted to the imperial government.
In winter 820, major events that tested Emperor Muzong's abilities to keep these circuits under control came. Wang Chengzong the military governor of Chengde, whose family had controlled Chengde since his grandfather Wang Wujun and whose forces Emperor Xianzong was unable to defeat (although Wang Chengzong himself eventually became apprehensive of Emperor Xianzong's might and submitted anyway), died. With Wang Chengzong having sent his sons Wang Zhigan (王知感) and Wang Zhixin (王知信) to Chang'an to serve as hostages in order to show his submission to the imperial government, his subordinates, who wanted to keep Chengde independent from the imperial government, supported Wang Chengzong's brother Wang Chengyuan to succeed him. Wang Chengyuan pretended to accept their support, but declared his loyalty to the imperial government and secretly petitioned Emperor Muzong to replace him.
Emperor Muzong reacted by, against the advice of the general Yang Yuanqing (楊元卿), moving Tian Hongzheng the military governor of Weibo—whose submission to the imperial government in 812 had been a crucial step in the Yuanhe Restoration and who had been a major participant in the subsequent campaigns against Chengde and Pinglu—to Chengde, Wang Chengyuan to Yicheng Circuit (義成, headquartered in modern Anyang, Henan), Liu Wu from Yicheng to Zhaoyi Circuit (昭義, headquartered in modern Changzhi, Shanxi), Li Su from Wuning Circuit (武寧, headquartered in modern Xuzhou, Jiangsu) to Weibo, and made Tian Hongzheng's son Tian Bu the military governor of Heyang Circuit (河陽, headquartered in modern Jiaozuo, Henan). Wang Chengyuan, despite the opposition of his soldiers, departed Chengde and turned control of the circuit over to Tian Hongzheng. Tian Hongzheng, however, was apprehensive that the soldiers under him—whom he had fought on the battlefield for years and many of whom bore hatred for him—would mutiny, and thus brought 2,000 Weibo soldiers to Chengde to serve as his personal guard. When he requested that the imperial government supply the salaries of these Weibo soldiers, however, the acting director of finances, Cui Ling (崔倰), a relative of the chancellor Cui Zhi, not understanding the seriousness of the situation, believed that it was the Chengde soldiers' responsibility to protect their military governor, refused. Tian was forced to return the Weibo soldiers to Weibo.
Meanwhile, in spring 821, Liu Zong the military governor of Lulong, who had taken power initially by killing his father Liu Ji and brother Liu Gun (劉緄), had grown fearful of his father's and brother's spirits, and wished to resign and become a Buddhist monk. He also requested an award to the soldiers, while ordering a number of officers that he felt were difficult to control, including Zhu Kerong (the grandson of a former military governor, Zhu Tao) to report to Chang'an, hoping that the imperial government would give them proper discipline and rewards such that they would become faithful to the imperial government. He further recommended that Lulong be divided into three circuits and recommended Zhang Hongjing, Xue Ping, and Lu Shimei (盧士玫) to take over the three circuits. Specifically, his division plan called for the circuit capital, You Prefecture (幽州), along with Zhuo Prefecture (涿州, in modern Baoding, Hebei), be given to Zhang; Ji (薊州, in modern Tianjin), Gui (媯州, in modern Zhangjiakou, Hebei), and Tan (檀州, in modern Beijing) Prefectures be given to Xue; and Ying (瀛州) and Mo (莫州, both in modern Cangzhou, Hebei) Prefectures be given to Lu. (Liu had made these recommendations on the bases that when Zhang ruled Hedong, which neighbored Lulong, Liu had often heard good opinions of Zhang's governance; that Xue was the son of Xue Song and familiar with the region; and that Lu was a relative of Liu's wife's.)
Emperor Muzong accepted Liu's submission, but did not fully implement Liu's partition plan; Ying and Mo were given to Lu Shimei, but the remaining prefectures were all given to Zhang, under the suggestion of the chancellors Cui Zhi and Du Yuanying, who did not understand the rationale of Liu's plan. Further, Zhu and the other officers that Liu sent to Chang'an were not given offices or salaries, and it was said that as they lacked income, they fell into financial desperation, even requiring loans for their food and clothing, despite their frequent submission of requests for offices to Cui and Du. When Zhang arrived at Lulong, he ordered Zhu and the others to return to Lulong, further angering them. Meanwhile, Zhang further drew the anger of the people and soldiers of Lulong over a number of actions:
In contrast to the past military governors' willingness to bear the difficulties with the people, including the weather conditions, when Zhang was arriving at You Prefecture, he was in a litter borne by eight men, shocking the people of You Prefecture.
Zhang Hongjing was solemn and arrogant, not willing to speak with the people, and he rarely accepted advice from guests and the army officers.
He gave much authority to his assistants Wei Yong (韋雍) and Zhang Zonghou (張宗厚), and these assistants were disrespectful of soldiers and extravagant in their living—such that, shocking to the people of You Prefecture, they were often feasting deep into the night and going home after midnight, with their guards loudly escorting them.
When Liu submitted to imperial authority, Emperor Muzong ordered a large cash reward for the Lulong soldiers, but Zhang Hongjing took 20% of the award for headquarter expenses.
The people of You Prefecture had venerated the leading figures of the Anshi Rebellion, An Lushan and Shi Siming, and referred to them as the "Two Holy Men." Zhang Hongjing, wanting to change this custom, had An and Shi exhumed and their caskets destroyed, causing resentment among the people.
In fall 821, when a low-level officer accidentally collided with Wei's guards, Wei ordered the officer whipped, but the other officers were unaccustomed to this kind of punishment and refused to carry out the punishment. Zhang Hongjing had the officers arrested. That night, the soldiers mutinied, killed Wei and several other staff member of Zhang's, and put Zhang under arrest. The next day, the mutineers began to regret their actions, but when they met Zhang to ask for forgiveness, Zhang did not speak at all. The mutineers believed that Zhang was not intending to pardon them, and instead supported Zhu Kerong's father Zhu Hui (朱洄) to serve as the acting military governor. Zhu Hui declined, but recommended Zhu Kerong, and the soldiers agreed.
Meanwhile, in fall 821, after the Weibo soldiers had departed from Chengde, the Chengde officer Wang Tingcou plotted a mutiny. One night, he led his soldiers and attacked Tian Hongzheng's headquarters, killing him, his staff, and their family members, and then taking over control of most of Chengde by killing those who disagreed with him. Niu Yuanyi (牛元翼), the prefect of one of Chengde's prefectures, Shen Prefecture (深州, in modern Hengshui, Hebei), tried to resist Wang Tingcou, but soon was besieged within the capital of Shen Prefecture. Meanwhile, Li Su planned a campaign against Wang and Zhu, but fell ill, and was replaced by Tian Bu as the military governor of Weibo. Emperor Muzong commissioned Pei Du, a key chancellor during Emperor Xianzong's reign, to oversee the entire operation against Lulong and Chengde, which also included such renowned imperial generals as Wu Chongyin and Li Guangyan and had some 150,000 soldiers in total, against the less than 10,000 soldiers that the rebels had.
However, by this point, the imperial treasury had been exhausted by Emperor Muzong's extravagance, and Pei's battle plans were being interfered with by Emperor Muzong's trusted imperial scholar Yuan Zhen. The imperial forces were unable to achieve quick victory over Chengde and Lulong rebels, and when Tian Bu tried to advance his forces, they took mutinied under the leadership of Shi Xiancheng. Tian tried to rally the remaining troops, which refused to follow his orders further. He committed suicide, and Shi, who nominally submitted to the imperial government and thus received imperial sanction, took over Weibo. The imperial government was forced to capitulate, and soon also named Zhu and Wang military governors of their circuits as well, ending the campaign against them. From this point on, until the eventual fall of the Tang dynasty altogether in 907, the imperial government was never again able to assert direct control over Chengde, Lulong, or Weibo.
