eastern capital Luoyang to defend against Weibo, were moved to Ru Prefecture (汝州, in modern Pingdingshan, Henan) to instead defend against Zhangyi, whose military governor Wu Shaoyang had died earlier, and it was said that this movement pleased Tian Hongzheng greatly. When Emperor Xianzong did not allow Wu Shaoyang's son Wu Yuanji to succeed Wu Shaoyang, Wu Yuanji reacted by openly pillaging the surrounding circuits, and Emperor Xianzong declared a campaign against Wu Yuanji in spring 815. Tian Hongzheng sent his son Tian Bu, with a detachment of 3,000 soldiers, to serve in the campaign. With Emperor Xianzong also having declared the military governor of Chengde Circuit, Wang Chengzong, a renegade — but not declared a campaign against Wang at that point — Tian Hongzheng led his troops to wait on the border with Chengde, and Wang repeatedly harassed his troops. Tian Hongzheng requested permission to enter Chengde territory, and Emperor Xianzong authorized him to advance to Bei Prefecture (貝州, in modern Xingtai). It was also said that it was because of Tian's loyalty to the imperial government that the military governor of Pinglu, Li Shidao, did not dare to openly aid Zhangyi. After Wu was defeated and captured by the imperial general Li Su in 817, Wang became fearful, and he made offers through Tian to submit to the imperial government. Tian relayed Wang's offers to the imperial government, and in spring 818, Emperor Xianzong accepted Wang's offer to send his sons Wang Zhigan () and Wang Zhixin () to the capital Chang'an as hostages and to submit two of Chengde's six prefectures to imperial control. Li Shidao initially also offered to do the same as Wang — sending his sons as hostages and submitting three of Pinglu's 12 prefectures — to show submission to the imperial government, but soon reneged on his offer. In anger, Emperor Xianzong declared a campaign against Pinglu. In the initial stages, Emperor Xianzong, at Pei's suggestion, had the Weibo forces remain at Weibo to rest themselves (and to prevent unnecessary expenditures, as once a circuit's troops left the circuit, the imperial treasury would be responsible for their expenditures) until winter 818, when under imperial orders Weibo forces under Tian Hongzheng crossed the Yellow River and approached Pinglu's capital prefecture Yun Prefecture, causing much alarm at Yun Prefecture. Tian scored several victories against Pinglu forces under the Pinglu officer Liu Wu, in spring 819.