Ma Su (190–228), courtesy name Youchang, was a military general and strategist of the state of Shu Han in the Three Kingdoms period of China. He was a younger brother of Ma Liang. Ma Su had conspicuous talent in military theories and was admired by the Shu chancellor Zhuge Liang. However, a tactical blunder by Ma Su at the Battle of Jieting resulted in Shu being dealt a huge defeat by Zhang He, a general of the rival state of Wei.
Much dramatisation shrouds the death of Ma Su. In the historical novel Romance of the Three Kingdoms as well as the Peking opera Loss of Jieting, Ma Su was said to have been executed on Zhuge Liang's order. However, according to the biographies of Ma Su and his close friend Xiang Lang in the Records of the Three Kingdoms, Ma Su had actually attempted to escape after his defeat at Jieting, but was captured. He eventually died of illness in prison before the ordered execution could be carried out.
A local of Yicheng, Xiangyang (present-day Yicheng, Hubei), Ma Su was one of the five brothers in the family, all of whom were renowned for their intellects, though Ma Su's elder brother Ma Liang was deemed to be the most talented among them all. Together with Ma Liang, Ma Su began his service under Liu Bei around 205, when Liu Bei was still a guest of Liu Biao in Jing Province (covering present-day Hubei and Hunan).
Since the start, Liu Bei's chief advisor Zhuge Liang had been impressed by Ma Su's expansive knowledge in military strategy. At some point before 219, Ma Su was transferred to Yuexi, a troubled commandery in the south. Yuexi was home to numerous indigenous tribes, many of whom refused to accept Liu Bei’s authority. It was the site of a significant tribal revolt led by Gaodingyuan in 218. With help from Li Yan who bent Gaodingyuan in a battle in 218, Ma Su did well in keeping order in the commandery. Before Liu Bei died in 223, he warned Zhuge Liang that Ma Su was not as talented as he seemed and should not be given important appointments. However, Zhuge Liang did not heed the warning, and Ma Su was made a personal military consultant to Zhuge soon after Liu died. The two would often hold discussions from dawn to dusk.
During the campaign against Meng Huo, Ma Su advised Zhuge Liang to win Meng Huo over to serve Shu by capturing and releasing him again until Meng Huo finally surrendered and joined Shu.
Performance in Jieting
In 228, Zhuge Liang launched his Northern Expeditions against Wei, Ma Su also proposed a plot to remove Sima Yi from command by causing discord within Wei by spreading rumors that Sima Yi intended to rebel and Cao Rui then removed him from command. Many suggested appointing either Wei Yan or Wu Yi (吴懿) as the vanguard commander, but Zhuge Liang chose the callow Ma Su instead.
Ma Su's forces encountered Zhang He's forces at Jieting. It was here that Ma Su made a serious tactical blunder. He had camped on top of a hill, believing the vantage point would provide him with a more advantageous position in terms of observation and a place of attack. The veteran general Wang Ping advised against Ma Su's decision, arguing that their water supply might be cut off and their forces surrounded. While his good counsel was rejected, Ma Su allowed Wang Ping to take 1,000 men and camp nearby the source of the Shu forces' water supply.
As Wang Ping predicted, Zhang He took advantage of Ma Su's mistake by striking at the Shu camp's water supply. Scattering Wang Ping's much smaller force, he succeeded in cutting off the enemy's water supply. The parched soldiers of Shu were easily defeated when Zhang He then launched an offensive on the main camp itself.
Records on Ma Su's death
Though he survived the battle, Ma Su's army was nearly annihilated (Wang Ping was able to regroup some scattered forces), so he was soon arrested and sentenced to execution by a reluctant and tearful Zhuge Liang as a way to soothe the masses. However, the addendum to Ma Liang's biography concerning Ma Su's death says Ma Su eventually died of illness in prison before an execution was actually carried out. Yet, another record from the biography of Xiang Lang stated that Xiang, as a close friend of Ma Su, assisted the latter in escaping by covering up Ma's jailbreak. Regardless, Ma Su was deemed by Zhuge Liang to hold major responsibility for the failure of the first Northern Expedition. Ma Su's wife and children were said to have been well taken care of by Zhuge Liang after Ma's death.