Li Su - During Emperor Muzong's Reign

During Emperor Muzong's Reign

In spring 820, Emperor Xianzong died and was succeeded by his son Emperor Muzong. Soon thereafter, Li Su was given the honorary chancellor title of Tong Zhongshu Menxia Pingzhangshi (同中書門下平章事). Further, in anticipation of potential further actions against two other circuits governed de facto independently — Chengde (成德, headquartered in modern Shijiazhuang, Hebei) and Lulong (盧龍, headquartered in modern Beijing) — Emperor Muzong made Li Su the military governor of Zhaoyi Circuit (昭義, headquartered in modern Changzhi, Shanxi). Later that year, when Wang Chengzong the military governor of Chengde died, his brother Wang Chengyuan offered to return control of the circuit to the imperial government. Emperor Muzong, in response, moved Tian Hongzheng the military governor of Weibo Circuit (魏博, headquartered in modern Handan, Hebei) — itself having previously been semi-independent from imperial rule but which had submitted to imperial command during Tian Hongzheng's governance — to Chengde, Wang Chengyuan to Yicheng, Liu Wu from Yicheng to Zhaoyi, Li Su from Zhaoyi to Weibo, and Tian Hongzheng's son Tian Bu to Heyang Circuit (河陽, headquartered in modern Luoyang, Henan).

The Chengde soldiers, however, had long resented Tian Hongzheng, as during Emperor Xianzong's reign Chengde and Weibo forces had often battled each other. Initially, with Weibo soldiers accompanying Tian Hongzheng to Chengde and protecting him, they did not act, but as soon as Weibo soldiers returned to Weibo in summer 821, the Chengde officer Wang Tingcou rose in mutiny and killed Tian Hongzheng. Upon hearing of Tian Hongzheng's death, Li Su changed into mourning clothes, and he stated to his soldiers:

The reason why the people of Wei Prefecture were able to receive imperial culture and have peace and happiness was Lord Tian. Now, the unlawful people of Zhen Prefecture dared to murder him because they take us lightly and think that there is no one from Wei who can avenge him. You, gentlemen, have received great grace from Lord Tian. How are you going to repay him?

The soldiers all wept in sadness. Meanwhile, Niu Yuanyi (牛元翼) the prefect of Shen Prefecture (深州, in modern Hengshui, Hebei), was not willing to follow Wang. Li Su, hearing this, sent his sword and jade belt to Niu, sending a message to him: "My father had used this sword to accomplish great things. I have also used this sword to capture Cai Prefecture. Now I give it to you, Lord, and you should use it to destroy Wang Tingcou." Niu was touched, and showed the sword and belt to his soldiers and stated, "I am willing to die for the empire." Li Su was then preparing an attack against Wang in conjunction with Niu, but suddenly fell ill again. Emperor Muzong thus made Tian Bu the military governor of Weibo to succeed him. Li Su was given the title of advisor to the Crown Prince, and allowed to return to the eastern capital Luoyang to try to recover from illness. However, he died there in winter 821. He was buried with great honors.