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Sima Yi
A Qing Dynasty illustration of Sima Yi
Born 179
Died September 7, 251(251-09-07) (aged 71–72)

Sima Yi (179 – 7 September 251), Zhongda, was a general and politician of the state of Cao Wei in the Three Kingdoms period. He is perhaps best known for defending Wei from Zhuge Liang's Northern Expeditions. His success and subsequent rise in prominence paved the way for his grandson Sima Yan's founding of the Jin Dynasty, which would eventually bring an end to the Three Kingdoms era. In 265 after the Jin Dynasty was established, Sima Yi was posthumously honoured as Emperor Xuan of Jin with the temple name of Gaozu.

Early life[]

Sima Yi was one of eight brothers, all of whom were famous due to their lineage. Each of them had a ending with the character Da (達). Because of this, the brothers were known collectively as the "Eight Da of Sima" (司馬八達). This was a term of respect, as other groups of eight talented administrators in previous eras had been referred to in this way.[1] His family resided in Luoyang when Dong Zhuo occupied the city, destroyed it, and moved the capital to Chang'an. Sima Yi's elder brother Sima Lang led the family to their ancestral home in Wen County (温縣; present-day Wen County, Henan), and then, correctly predicting that it would become a battlefield, moved them again to Liyang (黎陽; present-day Xun County, Hebi, Henan). In 194, as Cao Cao battled Lü Bu, Sima Yi accompanied his family back to Wen County.

Service under Cao Cao[]

Accounts on how Sima Yi joined the service of Cao Cao differ, but he accepted his first position in Cao's camp at the age of 30. According to the Book of Jin, Sima Yi believed that the Han Dynasty would soon come to an end, and felt no motivation to join Cao Cao, which had already taken control of the Han government. He refused Cao Cao's requests to serve, saying that he was suffering from a disease. Cao Cao did not believe Sima Yi's excuse, and sent agents to check on him at night. Sima Yi, knowing this in advance, stayed in bed all night and did not move. In 208, Cao Cao became Imperial Chancellor and ordered Sima Yi to serve him, saying "If he dallies, arrest him." Afraid of what would befall him, Sima Yi finally accepted the position of Wenxueyuan (文学掾).[2] However, according to the Weilüe, Cao Hong, Cao Cao's younger cousin, requested the presence of Sima Yi in order to start a friendship with the latter, who did not have a very high opinion of Cao Hong and feigned illness by carrying a cane in order to avoid meeting him. Cao Hong went to Cao Cao in anger and told him what had happened, after which Cao Cao directly requested the presence of Sima Yi. Only then did Sima Yi officially enter Cao Cao's service.[3]

Under Cao Cao, Sima Yi rose through the ranks of Dongcaoyuan (東曹掾; in charge of bringing officials into service), Registrar (主簿; an administrative position), and Major (司馬; position in charge of aids and advisors). In 215, when Cao Cao defeated Zhang Lu and forced him to surrender, Sima Yi advised that Cao Cao continue to advance south into Yi Province (covering present-day Sichuan and Chongqing), since Liu Bei had still not stabilised his control of that area. However, Cao Cao did not listen to his advice. Sima Yi was among other advisors who urged for the implementation of the tuntian system and for Cao Cao to take the title of a vassal king - "King of Wei".[2]

Service under Cao Pi[]

Even before Cao Cao's death, Sima Yi was close to his successor, Cao Pi. When Cao Pi was designated heir apparent to the vassal state of Wei in 216, Sima Yi was made his secretary. When Cao Cao wavered on choosing between Cao Pi and his younger brother Cao Zhi, Sima Yi was believed to be among those who backed Cao Pi and helped him secure the succession. Due to the fact that Sima Yi had been a long-time friend of Cao Pi since the latter held the position of General of the Household, he became greatly trusted when the latter ascended the throne. Sima Yi was also involved in Cao Zhi's demotion and removal from politics.[4]

In 225, Cao Pi advanced against the rival state of Eastern Wu, and entrusted Sima Yi with command over the capital in his absence. He compared Sima Yi to Xiao He, whose quiet contributions behind the battle lines earned him much praise.[2] Upon returning from the military expedition, Cao Pi once again praised his servant, saying "As I did battle in the east, you stayed in the capital and guarded our state against Shu in the west. When I go to battle in the west against Shu, I'll entrust you with defence against Wu in the east." Sima Yi was soon given the post of Lushang Shushi (録尚書事), which at that time held the same real power and responsibilities as Imperial Chancellor.

Service under Cao Rui[]

In 226, as Cao Pi laid on his deathbed, he entrusted his successor Cao Rui to the care of Sima Yi, Cao Zhen, and Chen Qun. When Cao Rui became Emperor of Wei, he trusted Sima Yi greatly and appointed him General of Agile Cavalry (驃騎大將軍)[5] and military commander of Yu and Jing provinces, placed him on the border between Wei and Wu to defend against Sun Quan's forces, and created him Marquis of Wuyang.

Xincheng Rebellion[]

Meng Da is killed at Xincheng by Sima Yi's soldiers.

In 220, Meng Da surrendered to Wei and Cao Pi entrusted him as Administrator of Xincheng. Sima Yi did not trust him, and argued his case to Cao Pi, but his advice was not taken.[4] In 227, Meng Da began making overtures to Wu and Shu, promising to turn against Wei when an opportunity presented itself. He was very slow to move in response to Zhuge Liang's urgings, however, and Zhuge Liang attempted to spur Meng Da into action by leaking his rebellious intentions to Shen Yi, the administrator of Weixing (魏興). When Meng Da learned that his plans had been discovered, he began raising troops in preparation for action.

Fearing quick action by Meng Da, Sima Yi sent him a letter saying "Long ago, you surrendered to our state, and we put you in charge of the defence of our borders against Shu. The people of Shu are foolish, and still hate you for not coming to Guan Yu's assistance. Kongming is the same, and he has been looking for a way to destroy you. As you probably suspect, the news of your rebellion is only his plot." Meng Da now believed that he was safe, and did not rush his preparations. He believed that Sima Yi, posted on the border of Wei and Wu, would require a month to go to Cao Rui and request permission to raise troops, then to reach Xincheng. However, Sima Yi was already on his way and reached Xincheng in eight days, quickly defeating the unprepared Meng Da, who was killed in the battle. This action contributed indirectly to the success at the Battle of Jieting and earned Sima Yi much praise.

Zhuge Liang's Northern Expeditions[]

When Cao Zhen, who had been leading the defence against Zhuge Liang's Northern Expeditions died in 231, Sima Yi took his position in command, and faced Zhuge Liang's armies for the first time in battle. Sima Yi kept his armies safe in fortifications, his strategy being to wait out the Shu armies who had a very difficult time keeping their armies supplied with provisions. He did not attempt to do battle with Zhuge Liang whatsoever, and was mocked by his own subordinates, who claimed he was the laughing stock of the world.[6] Unable to resist doing battle any longer, he allowed his generals to attack Shu's positions, but they were badly defeated and suffered losses including 3,000 soldiers, 5,000 suits of iron armour, and 3,000 crossbows.[7] When Zhuge Liang finally did retreat, Sima Yi ordered Zhang He to pursue, but Zhang was ambushed and killed.

A Qing Dynasty illustration of a battle between Zhuge Liang and Sima Yi

The second battle between Sima Yi and Zhuge Liang was in 234. Cao Rui again identified Shu's problem being keeping their army supplied, and ordered Sima Yi to keep his armies fortified and wait the enemy out. The two armies faced each other at Wuzhang Plains. Although being challenged many times by Zhuge Liang, Sima Yi did not send his armies to attack. To provoke Sima Yi, Zhuge Liang sent women's clothes to him, suggesting that he was a woman for not daring to attack. The Wei officers were enraged by this, but Sima Yi would not be provoked. To appease his officers, Sima Yi asked the Wei emperor Cao Rui for permission to engage the Shu forces. Cao Rui, understanding the situation, sent his advisor Xin Pi to Sima Yi telling the Wei forces to be patient.[8] In an attempt to engage the Wei forces, Zhuge Liang sent Sima Yi an emissary urging him to battle. Sima Yi, however, would not discuss military matters with the emissary, instead enquired about Zhuge Liang's tasks. The emissary replied that Zhuge Liang personally managed all major and minor matters in the military, from military tactics to meals for the night, but he consumes very little. Sima Yi then told an aide that Zhuge Liang would not last long.[9]

Sima Yi flees from the dead Zhuge Liang.

Following Zhuge Liang's death, the Shu forces quietly withdrew from their camps while keeping Zhuge Liang's death a secret. Sima Yi, convinced by the locals that Zhuge Liang had died, gave chase to the retreating Shu forces. Jiang Wei then had Yang Yi turn around and pretend to strike. Seeing this, Sima Yi feared that Zhuge Liang only pretended he was dead to lure him out, and immediately retreated. Word that Sima Yi fled from the already dead Zhuge Liang spread, spawning a popular saying, "A dead Zhuge scares away a living Zhongda" (死諸葛嚇走活仲達), referring to Sima Yi's style name. When Sima Yi heard of such ridicule, he laughingly responded, "I can predict the living, but not the dead."[2]

Expedition against Gongsun Yuan[]

After Guanqiu Jian had failed to defeat the forces of Gongsun Yuan in Liaodong, and Gongsun Yuan had declared himself Prince of Yan, Cao Rui put Sima Yi in charge of the next expedition against him. Sima Yi defeated Gongsun Yuan twice on the field of battle, and forced him to retreat to Xiangping (襄平; present-day Liaoyang, Liaoning), where he prepared for siege. Long rains brought a temporary break from the fighting, but as soon as they lifted, Sima Yi launched an all out attack. Gongsun Yuan and his sons were killed while attempting to flee.[10]

Service under Cao Fang and coup d'état[]

As Cao Rui laid on his deathbed, he had doubts about Sima Yi, and initially planned to exclude him from the regency of his successor Cao Fang.[11] He wanted to entrust Cao Fang to his uncle Cao Yu, to serve as the lead regent, along with Xiahou Xian (夏侯獻), Cao Shuang, Cao Zhao (曹肇), and Qin Lang. However, his trusted officials Liu Fang (劉放) and Sun Zi (孫資) were unfriendly with Xiahou Xian and Cao Zhao and were apprehensive about their becoming regents, and managed to persuade him to make Cao Shuang (with whom they were friendly) and Sima Yi (who was then with his troops at Ji (汲縣, in present-day Xinxiang, Henan), and to whom Liu Fang and Sun Zi were close to, as regents instead. Cao Yu, Cao Zhao, and Qin Lang were excluded from the regency.

Initially, Cao Shuang and Sima Yi shared power, but Cao Shuang quickly used a number of political maneuvers to honour Sima with honorific titles including Grand Tutor while stripping his actual power. Cao Shuang then made all important decisions and stopped consulting Sima Yi. Quickly, Cao Shuang's associates, including Deng Yang (鄧颺), Li Sheng (李勝), He Yan (何晏), and Ding Mi (丁謐),[12] who were known for their talents but lack wisdom, all became powerful, and they excluded other officials who would not associate with them from positions of power.[13] Sima Yi was still given military authority (including command in repelling a major Eastern Wu attack in 241), but no real authority on governance.

Incident at Gaoping Tomb[]

In 244, Cao Shuang, who wanted to garner for himself a military reputation as well, made a major attack against Shu's major border city of Hanzhong, without careful logistics planning. The battles themselves were inconclusive, but after Wei forces ran out of food supplies, Cao Shuang was forced to withdraw at great loss of life.[14] Despite his failure on the battlefield, however, Cao Shuang held onto power firmly. In 247, Sima Yi, upset at his actual powerlessness, claimed that he was ill and retired from government service. Cao Shuang sent Li Sheng to determine whether or not Sima Yi was truly ill, and Sima deceived him by acting senile in his presence.[15]

In 249, Sima Yi made his move. While Cao Fang and Cao Shuang were outside the capital on an official visit to Cao Rui's tomb, Sima Yi, with support from a number of anti-Cao Shuang officials, claiming to have an order from Empress Dowager Guo to do so, closed all city gates of Luoyang and submitted a report to Cao Fang, accusing Cao Shuang of dominating and corrupting the government and demanding that Cao Shuang and his brothers be deposed. Cao Shuang was stricken by panic and did not know how to react, and even though his senior advisor Huan Fan recommended that he take Cao Fang to the secondary capital Xuchang and then resist Sima Yi with his troops, Cao chose to surrender his troops and powers, under promise by Sima that he would still be able to maintain his wealth. However, Sima Yi soon reneged on the promise and had Cao Shuang and his associates, as well as their clans, executed on charges of treason.[16] Although not a popular theory, some believe this intention of betrayal to the Cao line stretched as far back as Sima Yi's days of serving Cao Cao. This is because Cao Cao once told Cao Pi that Sima Yi was hiding an ambition, and would not die merely serving another.[2]

After Sima Yi's takeover, he carefully but inexorably removed people who were actual or potential threats to his authority. Yet, at the same time, he strived to distance himself from the patterns followed by the man his actions seemed to mirror most - Cao Cao; when Cao Fang offered him the nine bestowments, he strenuously refused them, only accepting them after more than three offers. The 18-year-old Cao Fang left himself in a vulnerable position by going so far as to grant one of his followers such influence; Sima Yi, however, had the support of the people by removing corruption and inefficiency that characterised Cao Shuang's regency and promoting a number of honest officials. He was offered the title of Imperial Chancellor, but refused.[5]

Wang Ling's case[]

In 249, the powerful general Wang Ling, who was in charge of the key southeastern city of Shouchun (壽春, in present-day Lu'an, Anhui) began to plan a revolt against Sima Yi's hold on power, in association with Cao Biao (曹彪), the Prince of Chu and a son of Cao Cao (whom he planned to replace Cao Fang with as emperor). In 251, Wang Ling was ready to carry out his plans when his associates Huang Hua (黃華) and Yang Hong (楊弘) leaked the plan to Sima Yi. Sima Yi quickly advanced east before Wang Ling could be ready and promised to pardon him. Wang Ling knew that he was not ready to resist, so he submitted, but Sima Yi again reneged on his promise and forced Wang Ling and Cao Biao to commit suicide. Wang Ling's clan and the clans of his associates were all slaughtered.

Having secured his family's control of Cao Wei, Sima Yi died in 251 and was succeeded by his son Sima Shi.


Sima Yi was married to Zhang Chunhua.


After the fall of the Western Jin Dynasty in 316, the belief began to shift from the popular ideal that Cao Wei was the rightful successor to the Han Dynasty toward a sympathetic view of Shu Han. Before this change, Sima Yi was seen as a righteous figure in the Book of Jin and was practically deified. Afterwards, Sima Yi began to be vilified; a view which was epitomised in Luo Guanzhong's historical novel Romance of the Three Kingdoms. In the novel, Sima Yi was portrayed as the dedicated servant of Cao Cao, obsessed with his ideals even to the point of honing his example of usurping power against a weak ruler and using it to bring down Cao Cao's own descendants. In terms of history, many of the accounts are either contradicted or simply do not exist and were most likely borrowed from either the elements of Luo Guanzhong's imagination or from folktales that had been passed down through the ages.

As Sima Yi's contributions toward Wei are substantial, the debate of his legacy lies within what motivated his actions. A debate, that has continued to this day and will most likely never be resolved, as to whether Sima Yi was acting in a benevolent way, such as Huo Guang did during the Han Dynasty, or whether he was acting out of pure ambition, comparable to Wang Mang's short-lived Xin Dynasty. However, he died only a few years after forcibly regaining his power from Cao Shuang, leaving no definitive answer to his intentions for future generations.


One legend about Sima Yi is that he could turn his head 180° around on his neck to look backwards without turning his body. This characteristic was called the "turning-back of the wolf" (狼顧), supposedly based on the fact that wolves are cautious and aware of everything going on around them as though they had eyes in the back of their heads. It is said that Cao Cao heard this rumour and wanted to test it for himself. According to the legend, he came up behind Sima Yi and called out his name, and indeed Sima's head did turn completely around.[2] According to the Book of Jin, when Cao Cao saw this, he grew cautious of Sima Yi, saying "This man is hiding great ambition". Cao Pi would comment on Sima Yi, "This man probably has no intention of ending his life as a mere servant."

Modern references[]

Sima Yi appears as a playable character in Koei's Dynasty Warriors and Warriors Orochi video game series.

In the collectible card game Magic: The Gathering there is a card named "Sima Yi, Wei Field Marshal", in the Portal Three Kingdoms set.

Chan Mou's manhua series The Ravages of Time is a fictionalised retelling of the history of the late Eastern Han Dynasty and the Three Kingdoms, with Sima Yi as the central character.

See also[]


  1. Sakaguchi 2005:158
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Book of Jin, vol. 1.
  3. Weilüe
  4. 4.0 4.1 Sakaguchi 2005:160
  5. 5.0 5.1 Watanabe 2006:283
  6. Sakaguchi 2005:161
  7. Records of Three Kingdoms note Spring and Autumn Annal of Han and Jin.
  8. Watanabe 2006:270
  9. Watanabe 2006:272
  10. Watanabe 2006:278
  11. Sakaguchi 2005:204
  12. Watanabe 2006:280, Sakaguchi 2005:162
  13. Sakaguchi 2005:50
  14. Sakamoto 2005:51
  15. Watanabe 2006:281
  16. Sakamoto 2005:162, Watanabe 2006:282


  • Fang Xuanling, Book of Jin vol. 1.
  • Yu Huan, Weilüe.
  • Luo Guanzhong, Romance of the Three Kingdoms.
  • Sakaguchi, Wazumi (ed.) (2005) 坂口和澄・著 Seishi Sangokushi Gunyu Meimeiden 『正史三國志群雄銘銘傳』 Kojinsha:Tokyo.
  • Watanabe, Seiichi (ed.) (2006) 渡辺精一・監修 Moichidomanabitai Sangokushi 『もう一度学びたい 三国志』 Seitosha:Tokyo.

External links[]

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