Li Xilie
By 783, when Li Xilie was openly defying the imperial government, the chancellor Lu Qi, resentful of the senior official Yan Zhenqing, suggested Emperor Dezong to send Yan to Huaixi to try to persuade Li Xilie to resubmit. Li Mian, seeking that Yan's mission would be fruitless and that he was heading for certain death, submitted an objection and tried to intercept Yan on the way, but was unable to do so. Yan was subsequently detained by Li Xilie, although Li Xilie's subordinates Zhou Zeng (周曾), Wang Bin (王玢), and Yao Dan (姚憺) were in secret communications with Li Mian and hoping to replace Li Xilie and replace him with Yan. Soon, their plot was discovered, however, and Li Xilie killed them. Subsequently, when the imperial general Emperor Dezong sent to attack Li Xilie, Geshu Yao (哥舒曜), was put under siege by LI Xilie at Xiangcheng (襄城, in modern Xuchang, Henan), Emperor Dezong ordered Li Mian and Liu Dexin (劉德信) to aid Geshu. Li Mian, believing that since Li Xilie was attacking Xiangcheng, Xu Prefecture (許州, in modern Xuchang) would be easy to capture, and once Xu Prefecture fell, Li Xilie would be forced to lift the siege on Xiangcheng. He therefore ordered Liu and Tang Hanchen (唐漢臣) to attack Xu Prefecture. Before Liu and Tang could reach Xu Prefecture, however, Emperor Dezong sent an edict ordering them to stop. Liu and Tang were surprised and dismayed, and they withdrew, and they became careless in their retreat. They were ambushed by Li Xilie's officer Li Kecheng (李克誠), and suffered massive losses. With Li Mian fearful that Luoyang would be under attack, he sent an army under Li Jian (李堅) with 4,000 men to Luoyang to aid it, but subsequently, with the return path cut off by Li Xilie, they were unable to return to Bian Prefecture. From that point on, Yongping itself was in a precarious position, unable to aid Geshu and finding it difficult to stand against Li Xilie.