Wang Chengzong
On July 13, 815, before dawn, Wu Yuanheng was set to go to the palace for a meeting with Emperor Xianzong. As he left his house, suddenly, arrows were fired at his train. His servants all fled, and the assassins seized Wu and his horse, and then decapitated him, taking his head with them. The assassins also attacked another official who favored the campaign, Pei Du, but was unable to kill Pei. The people at the capital were shocked, and imperial guards were assigned to protect chancellors. The officials, for some time, would not dare to leave their houses until dawn. The assassins sent letters to the imperial guards and the governments of Jingzhao Municipality (京兆, i.e., the Chang'an region) and the counties, threatening to kill anyone who dared to pursue them, and it was said that the officials thus did not hunt for them diligently, despite Emperor Xianzong's stern orders. Meanwhile, a group of eight Chengde officers stationed at Chang'an, headed by Zhang Yan (). Wang Chengzong's uncle Wang Shize (), who had become a general in the imperial Shence Army after a dispute with Wang Chengzong, submitted a petition accusing Wang Chengzong of having sent Zhang and the other Chengde officers to kill Wu Yuanheng. Emperor Xianzong had Zhang and the others arrested and interrogated by the mayor of Jingzhao, Pei Wu (), and the imperial censor Chen Zhongshi (). Under intense interrogation, probably including torture, Zhang and the others confessed to assassinating Wu and were executed. The assassins sent by Li Shidao fled. Emperor Xianzong declared a five-day mourning period for Wu Yuanheng and gave him great posthumous honors.