李勉
In 775, the soldiers stationed at the important base Heyang (河陽, in modern Jiaozuo, Henan) mutinied and expelled their commander Chang Xiuming (). Emperor Daizong made Ma the commander of Heyang to replace Chang. In 776, following the death of Tian Shenyu () the acting military governor of Biansong Circuit (汴宋, headquartered in modern Kaifeng, Henan), Tian's subordinate Li Lingyao seized the control of the circuit. Initially, Emperor Daizong tried to appease Li Lingyao by making him the acting military governor, but after Li Lingyao continued to be defiant of imperial authorities, Emperor Daizong commissioned Ma, Li Zhongchen, Li Mian, assisted by Chen Shaoyou () and Li Zhengji, to attack Biansong. In fall 775, Ma and Li Zhongchen rendezvoused at Zheng Prefecture. Li Lingyao launched a surprise attack against their forces and causing them to withdraw; a large portion of Li Zhongchen's army, from Huaixi Circuit (淮西, headquartered in modern Zhumadian, Henan), deserted, while the people of Zheng Prefecture panicked and fled to the eastern capital Luoyang. Li Zhongchen wanted to retreat, but Ma opposed, stating, "We are regular troops attacking rebels. Why do we worry about defeat? Why do we give us this chance for battlefield accomplishments?" He dug in, and in response, Li Zhongchen gathered his soldiers and also dug in. They then moved toward Bian Prefecture, with Ma marching north of the Bian River (a canal connecting the Yellow River and the Huai River, flowing through Bian Prefecture) and Li Zhongchen marching south of the Bian River. They were joined by Chen's forces, and together they battled Li Lingyao's forces to the west of Bian Prefecture's capital, defeating Li Lingyao. Li Lingyao withdrew within the capital, and Ma and Li Zhongchen put it under siege. After they further defeated relief forces commanded by Tian Yue (the nephew of Tian Chengsi, who was allied with Li Lingyao), Li Lingyao fled but was eventually captured by Li Mian's forces and delivered to Chang'an to be executed. Ma, knowing that Li Zhongchen was fierce and cruel, decided not to contend with Li Zhongchen as to the credits for the victory and therefore refused to enter Bian Prefecture's capital. Li Zhongchen entered Bian Prefecture and, on his subsequent reports, credited only himself, as Ma predicted, going as far as killing the Biansong general Li Senghui (), who had turned against Li Lingyao and who also contributed much to the victory.