唐德宗建中二年发动对淄青、成德、魏博以及山南东道四节度使的讨伐战争,当年淮西节度使李希烈平山南东道梁崇义,三年王武俊以成德请降。但不久幽州、成德又联同魏博、淄青拒命,淮西也与之交通而叛唐,德宗把注意力转移到南战场对付李希烈。四年十月准备到南战场解襄城之围,救援哥舒 In the second year of the establishment of Tang Dezong, he launched a crusade against the four leaders of Zqing, Chengde, Weibo and Shannan Roads, when Huai Xi Jiedushi made Li Xilie Ping Shannan Dong Liangchongyi three years and Wang Wujun invited Cheng De to drop. But soon you state, Chengde and Weibo, Ziqing refused to appoint, Huaixi also with the traffic and betrayed the Tang, Dezong turned his attention to the South battlefield against Li Xilai. Four years in preparation for the battlefield to the south of battlefield Xiang Xiang, rescue Ge Shu