Tibetan forces declared Emperor Suzong 's cousin Li Chenghong the Prince of Guangwu the Emperor of Tang .
Forces withdrew within the course of a month due to the Tang people 's resistance efforts and counterattacks commanded by Guo Ziyi .
Tibetan forces declared Emperor Suzong 's cousin Li Chenghong the Prince of Guangwu the Emperor of Tang , although they withdrew within the course of a month due to the Tang people 's resistance efforts and counterattacks commanded by Guo Ziyi .