Sima Yi (179 – 7 September 251), courtesy name Zhongda, was a military general, government official and regent of the state of Cao Wei in the Three Kingdoms period. He is best known for defending Wei from a series of invasions between 230 and 234 by Wei’s rival state, Shu Han. His success and subsequent rise to power as the regent of Wei paved the way for the establishment of the Jin dynasty (265-420), which was founded by his grandson Sima Yan. In 265, after Sima Yan became emperor, he honoured his grandfather with the posthumous title Emperor Xuan of Jin and the temple name Gaozu.
A Qing dynasty illustration of Sima Yi
|Grand Tutor (太傅)|
240 – 7 September 251
|Preceded by||Zhong Yao|
|Succeeded by||Sima Fu|
|Manager of the Affairs of the Masters of Writing (錄尚書事)|
240 – 240
|Succeeded by||Sima Shi|
|Palace Attendant (侍中)|
240 – 240
221 – 226
|Grand Commandant (太尉)|
13 February 235 – 238
|Preceded by||Hua Xin|
|Succeeded by||Man Chong|
16 March 230 – 13 February 235
|Preceded by||Cao Zhen|
|Succeeded by||Cao Yu|
|General of Agile Cavalry (驃騎將軍)|
January or February 227 – 16 March 230
|General Who Pacifies the Army (撫軍將軍)|
224 – January or February 227
|Monarch||Cao Pi / Cao Rui|
|Right Supervisor of the Masters of Writing (尚書右僕射)|
221 – 226
|Palace Assistant Imperial Clerk (禦史中丞)|
220 – 221
|Master of Writing (尚書)|
220 – 220
Wen County, Han dynasty
|Died||7 September 251 (aged 72)
Luoyang, Wei dynasty
|Resting place||Mengjin County, Henan|
|Occupation||General, official, regent|
|Courtesy name||Zhongda (仲達)|
|Posthumous name||Emperor Xuan (宣皇帝)|
|Temple name||Gaozu (高祖)|
|Peerage||Marquis of Wuyang
Sima Yi's ancestral home was in Xiaojing Village (孝敬裏), Wen County (溫縣), Henei Commandery (河內郡), which is in present-day Zhaoxian Town, Wen County, Henan. His ancestor was Sima Ang, one of the rulers of the Eighteen Kingdoms in the transition from the Qin dynasty to the Han dynasty. In the early Han dynasty, Sima Ang's kingdom, which was based in Henei (河內; in present-day Henan), became a commandery of the Han Empire and his descendants had lived there since. Sima Jūn (司馬鈞), an eighth-generation descendant of Sima Ang, served as a general of the Han Empire. Sima Jūn's son, Sima Liang (司馬量), and Sima Liang's son, Sima Jùn (司馬儁), both served as commandery administrators. Sima Jùn's son, Sima Fang, served as the Intendant of Jingzhao (京兆尹) in the Eastern Han dynasty. Sima Yi (Zhongda) was Sima Fang's second son.
Sima Yi had one elder brother, Sima Lang (Boda), and six younger brothers (in decreasing order of seniority): Sima Fu (Shuda), Sima Kui (Jida), Sima Xun (Xianda), Sima Jin (Huida), Sima Tong (Yada) and Sima Min (Youda). The eight Sima brothers were collectively known as the "Eight Das"[a] because their courtesy names all ended with da (達).
Sima Yi displayed intelligence and great ambitions at a young age. He was knowledgeable and well versed in Confucian classics. When chaos broke out in China towards the end of the Eastern Han dynasty, Sima Yi often expressed sympathy and concern for the people. Before he reached adulthood around the age of 19, Sima Yi once met Yang Jun (楊俊), a commandery administrator who was known for spotting talents. Yang Jun described him as an "extraordinary talent". Cui Yan, a friend of Sima Yi's elder brother Sima Lang, once said, "[Sima Yi] is intelligent, decisive and unique. [Sima Lang] can't be compared to him."
Sima Yi and his family used to live in the imperial capital, Luoyang, where his father Sima Fang served as a government official. In 191, when the warlord Dong Zhuo dominated the Han central government and wanted to relocate the imperial capital to Chang'an, Sima Fang ordered Sima Lang to bring the entire Sima family out of Luoyang and return to their ancestral home in Wen County, Henei Commandery. Some months later, as Sima Lang foresaw that chaos would break out in Henei Commandery, he relocated his family to Liyang Commandery (黎陽郡; around present-day Xun County, Henan). In the mid-190s, when war broke out between the warlords Cao Cao and Lü Bu, Sima Lang brought his family out of Liyang Commandery and returned to their home in Wen County, Henei Commandery.
In 201, the administrative office of Henei Commandery nominated Sima Yi to join the civil service as a shangji yuan (上計掾; clerk in charge of records). At the time, the warlord Cao Cao, who then held the position of Minister of Works (司空) in the Han imperial court, heard of Sima Yi's talent and wanted to recruit him to serve in the administration. Sima Yi saw that the Han Empire's future was bleak and did not want to serve, so he lied that he suffered from paralysis and stayed at home. Cao Cao's spies reported that they saw Sima Yi lying motionless in bed. One day, while Sima Yi was drying his books under the sun, there was a sudden downpour so he rushed out to grab his books and was seen by a maid. Sima Yi's wife, Zhang Chunhua, feared that the maid would leak out news that Sima Yi was well and get their family into trouble, so she killed the maid to silence her.
When Cao Cao became the Imperial Chancellor in 208, he sent an official to recruit Sima Yi to serve as a wenxue yuan (文學掾; an assistant clerk) in his administration. He also instructed the official to arrest Sima Yi if he dawdled. Sima Yi became afraid so he accepted the appointment. Although he was initially assigned to be an attendant to the crown prince,[b] he was later reassigned to other positions, including: Gentleman of the Yellow Gate (黃門侍郎), Consultant (議郎), Officer in the East Bureau of the Imperial Chancellor's Office (丞相東曹屬), and Registrar in the Imperial Chancellor's Office (丞相主簿).
In 215, after Cao Cao defeated the warlord Zhang Lu in Hanzhong Commandery at the Battle of Yangping, Sima Yi urged him to capitalise on the momentum to press on and attack his rival, Liu Bei, who was in the neighbouring Yi Province (益州; covering present-day Sichuan and Chongqing). Sima Yi pointed out that since Liu Bei had only recently seized control of Yi Province from Liu Zhang, he had yet to establish a strong foothold in the province. However, Cao Cao rejected Sima Yi's idea and said that he was already content with having Longyou (隴右; covering parts of present-day Gansu and Shaanxi). He then turned his attention towards his other key rival, Sun Quan.
Sun Quan sent an emissary to meet Cao Cao, requesting to make peace and expressing his willingness to pledge allegiance to Cao Cao. He also urged Cao Cao to seize the throne from Emperor Xian and declare himself emperor. In response to Sun Quan's suggestion, Cao Cao remarked, "This rascal wants me to put myself on top of a fire!" However, Sima Yi told him, "The Han dynasty is in decline. Your Lordship controls nine-tenths of the Han Empire. You're in a position to take the throne. Sun Quan's submission is the will of Heaven. Previously, during Yu’s time and throughout the Xia, Shang and Zhou dynasties, the rulers who did not hesitate when they should take the throne were the ones who truly understood Heaven's will." Cao Cao ultimately never usurped the throne from Emperor Xian and remained nominally a subject of the Han Empire until his death.
In 216, after Emperor Xian promoted Cao Cao from a duke to a vassal king under the title "King of Wei" (魏王), Sima Yi became an adviser to Cao Cao's son and heir apparent, Cao Pi. Cao Pi highly regarded and respected Sima Yi for his brilliance. Along with Chen Qun, Wu Zhi and Zhu Shuo (朱鑠), Sima Yi was one of Cao Pi's close aides and one of his "Four Friends". Before Cao Pi became his father's heir apparent in 216, he engaged in a power struggle against his younger brother Cao Zhi over the succession. During this time, Sima Yi was believed to be among those who secretly backed Cao Pi and helped him win the position of heir apparent. He also allegedly had a hand in Cao Zhi's demotion and removal from politics after Cao Pi became the emperor.
When Sima Yi was appointed as an Army Major (軍司馬), he suggested to Cao Cao to stockpile food supplies and maintain their defences at the same time because there were more than 200,000 people who were unable to sustain themselves through farming. Cao Cao accepted his idea and implemented a policy for the people to farm and stockpile grain.
Sima Yi also warned Cao Cao about Hu Xiu (胡修) and Fu Fang (傅方), who respectively served as the Inspector of Jing Province and the Administrator of Nanxiang Commandery (南鄉郡; in Jing Province) at the time. He said that Hu Xiu was violent while Fu Fang was arrogant, so they should not be entrusted with the important responsibility of guarding the border at Jing Province. Cao Cao ignored him. In 219, during the Battle of Fancheng, while Cao Cao's general Cao Ren was besieged by Liu Bei's general Guan Yu in Fan (樊; or Fancheng, present-day Fancheng District, Xiangyang, Hubei), Cao Cao ordered Yu Jin to lead reinforcements to lift the siege on Fancheng. However, the reinforcements were destroyed in a flood and Yu Jin surrendered to Guan Yu. As Sima Yi foresaw, Hu Xiu and Fu Fang defected to Guan Yu, placing Cao Ren in an even more perilous situation.
Upon learning of Yu Jin's defeat, Cao Cao felt that the Han imperial capital at Xu (許; present-day Xuchang, Henan) was too near enemy territory, so he considered moving the capital further north into Hebei. Sima Yi and Jiang Ji said, "Yu Jin's defeat was not due to flaws in our defences, nor would it significantly affect us. Moving the capital is showing our weakness to the enemy. It'll cause panic in the regions around the Huai and Mian rivers. Sun Quan and Liu Bei seem close to each other, but they actually don't trust each other. Sun Quan will feel very uneasy upon seeing Guan Yu's victory, so we should incite him to attack Guan Yu's base in Jing Province. This will lift the siege on Fancheng." Cao Cao heeded their advice. Sun Quan later sent his general Lü Meng to attack Gong'an County and invade Jing Province in the winter of 219–220. Guan Yu was captured and executed by Sun Quan's forces.
Cao Cao wanted to relocate residents in Jing Province and Yingchuan Commandery (潁川郡) further north as he felt that they were too close to enemy territory in the south. Sima Yi, however, advised him against doing so and said, "The Jing and Chu regions are unstable. The people are easy to move but hard to pacify. As Guan Yu has been recently defeated, bad people will go into hiding. If we move the good people, we might cause them to feel distressed and unwilling to return to our side." Cao Cao heeded Sima Yi's advice. The people affected by the Battle of Fancheng later managed to revert back to their original livelihoods before the battle.
When Cao Cao died in Luoyang in March 220, there was much apprehension in the imperial court. Sima Yi ensured that Cao Cao’s funeral was held in an orderly fashion, and in doing so he earned the respect of officials within and outside the central government. He moved to Ye (鄴; in present-day Handan, Hebei) later.
After Cao Pi succeeded his father as the (vassal) King of Wei (魏王) and Imperial Chancellor of the Han Empire in early 220, he enfeoffed Sima Yi as the Marquis of Hejin Village (河津亭侯) and appointed him as his Chief Clerk (長史). Later, when Sun Quan led his forces to attack Cao Pi's territories in Jing Province, some officials rejected the idea of resisting Sun Quan since Fan (樊; present-day Fancheng District, Xiangyang, Hubei) and Xiangyang lacked food supplies. At the time, Cao Ren, who was defending Xiangyang, had been reassigned from Fan to defend Wan (宛; present-day Wancheng District, Nanyang, Henan). Sima Yi said, "Sun Quan has recently defeated Guan Yu. At this time, he’ll be thinking of defending his newly acquired territories (rather than attacking us), so he’ll definitely not pose a threat to us. Xiangyang's land and water routes are crucial to its defences against enemy attacks, so we cannot abandon the city." Cao Pi ignored Sima Yi's advice. As Sima Yi predicted, Sun Quan did not attack them after Cao Ren gave up on Xiangyang and Fan. Cao Pi regretted not listening to him.
In late 220, Cao Pi usurped the throne from Emperor Xian, ended the Eastern Han dynasty, and declared himself emperor of the newly established state of Wei. Cao Pi first appointed Sima Yi as a Master of Writing (尚書) but later reassigned him to be an Army Inspector (督軍) and Palace Assistant Imperial Clerk (禦史中丞). He also promoted Sima Yi from a village marquis to a district marquis under the title "Marquis of Anguo District" (安國鄉侯).
In 221, Sima Yi was removed from his post as an Army Inspector and was appointed as a Palace Attendant (侍中) and Right Supervisor of the Masters of Writing (尚書右僕射).
Three years later, in 224, Cao Pi went on a tour of the south to inspect his forces in the areas near the Wei–Wu border. Sima Yi remained behind to defend Xuchang and his marquis title was changed to "Marquis of Xiang District" (向鄉侯). He was appointed General Who Pacifies the Army (撫軍將軍) and placed in command of 5,000 troops, in addition to holding the positions of Official Who Concurrently Serves in the Palace (給事中) and Manager of the Affairs of the Masters of Writing (錄尚書事). When Sima Yi declined to accept these appointments, Cao Pi told him, "I'm so busy with state affairs that I've been working through both day and night and have hardly a moment for rest. (When I entrust you with these responsibilities,) I'm not commending you, but rather, I need you to help me share my burden."
In 226, Cao Pi led his armies to attack Sun Quan and left Sima Yi behind to defend and govern the imperial capital in his absence, as well as providing reinforcements and supplies for his armies at the frontline. Before departing, Cao Pi issued a decree: "I am deeply concerned about what happens after I die. This is why I entrust you with this responsibility. Even though Cao Shen made many contributions on the battlefield, Xiao He played a more important role than him. Can I be free of worries I have about the west (referring to the rival state Shu in the west)?" Cao Pi later returned from Guangling Commandery (廣陵郡) to Luoyang and he told Sima Yi, "When I'm in the east, you'll be in charge of the west; when I'm in the west, you'll be in charge of the east." Sima Yi remained behind to guard Xuchang.
In mid 226, when Cao Pi became critically ill, he summoned Sima Yi, Cao Zhen, Chen Qun and others to meet him in the south hall of Chonghua Palace (崇華殿), where he ordered them to assist his son Cao Rui after his death. Cao Pi also told Cao Rui, "You should be wary of these three men, but don't doubt them."
After Cao Rui became the Wei emperor, he elevated Sima Yi from the status of a district marquis to a county marquis under the title "Marquis of Wuyang (County)" (舞陽侯). Around the time, Sun Quan attacked Jiangxia Commandery (江夏郡; around present-day Xinzhou District, Wuhan, Hubei) and sent his generals Zhuge Jin and Zhang Ba (張霸) to attack Xiangyang. Sima Yi led Wei forces to resist the Wu invaders, defeated Zhuge Jin, and killed Zhang Ba and more than 1,000 Wu soldiers. In recognition of Sima Yi's efforts, Cao Rui promoted Sima Yi to General of Agile Cavalry (驃騎將軍).
Later that year, Sima Yi received news that Meng Da, a former Shu general who had defected to Wei, was planning to rebel against Wei and return to Shu. Earlier, during Cao Pi's reign, he had warned Cao Pi that Meng Da was untrustworthy, but Cao Pi ignored him. He was proven right after Cao Pi’s death.
Sima Yi wrote a letter to Meng Da to distract and confuse him while preparing to suppress the rebellion. While Meng Da was stuck in a dilemma on whether to rebel or not, Sima Yi swiftly assembled his troops and led them to attack Meng Da's base in Shangyong Commandery (上庸郡; around present-day Zhushan County, Hubei). He reached there within eight days and ordered his subordinates to lead separate detachments to block Meng Da's reinforcements from Shu and Wu.
Meng Da was taken by surprise as he did not expect Sima Yi to show up at Shangyong Commandery so quickly. Sima Yi's army attacked the city from eight different directions over six days. After the sixth day, Meng Da's nephew Deng Xian (鄧賢) and subordinate Li Fu (李輔) opened the city gates and surrendered to Sima Yi. Meng Da was executed and his head sent to the Wei capital Luoyang; more than 10,000 captives were taken. Sima Yi returned to Wan in triumph.
While he was in charge of Jing and Yu provinces, Sima Yi encouraged and promoted agriculture and reduced wastage of public funds. The people of the southern lands were happy and showed their support for him.
Shen Yi, a former subordinate of Meng Da, had remained in Weixing Commandery (魏興郡; around present-day Ankang, Shaanxi) for a long time and had become deeply entrenched there. All these years, he had been illegally using the Wei emperor's name to carve official stamps and seals, and giving them to others. After hearing of Meng Da's downfall, he became worried that he would be the next target of Sima Yi’s crackdown on traitorous officials. Around the time, as Sima Yi had just suppressed Meng Da's rebellion, many regional officials came to present gifts and congratulate him. Sima Yi sent a messenger to provoke Shen Yi and lure him into a trap. When Shen Yi came to confront him, he fell into the trap and was captured and sent to the imperial capital. Sima Yi also relocated to You Province more than 7,000 households who used to live in Shangyong Commandery. The Shu military officers Yao Jing (姚靜), Zheng Ta (鄭他) and others later brought more than 7,000 men with them to surrender to Sima Yi.
At the time, among the thousands of people who migrated to Wei from Shu, many were unregistered residents, so the Wei government wanted to have them officially registered as citizens of Wei. The Wei emperor Cao Rui summoned Sima Yi back to Luoyang and sought his opinion on this issue. Sima Yi said, "The enemy seized these people through deception and now abandon them. It's advisable to have them registered. This way, they will feel happy and at ease." Cao Rui then asked him which of Wei's two rival states (Wu and Shu) they should attack first. Sima Yi replied, "The people of Wu know that we are not adept in naval warfare, hence they dare to live in Dongguan (東關). In attacking an enemy, we should always block its throat and strike its heart. Xiakou (夏口) and Dongguan are the enemy's heart and throat. If we can move our land forces to Wan (皖)[c] to lure Sun Quan to advance east, and take advantage of Xiakou's low defences by sending our navy to attack it, it'll be like an army from Heaven descending (upon the enemy) and they'll definitely be defeated." Cao Rui agreed with Sima Yi's view and ordered him to return to his post at Wan (宛; in present-day Nanyang, Henan).
In 230, Sima Yi was promoted to General-in-Chief (大將軍), appointed Grand Chief Controller (大都督), and given a yellow axe (黃鉞; a ceremonial axe given to newly appointed generals). The Wei emperor Cao Rui put him and Cao Zhen in charge of defending Wei's western borders from attacks by its rival state, Shu, which had been launching invasions since 227. The army led by Sima Yi passed through Zhuoshan (斫山) and Xicheng County (西城縣; present-day Ankang, Shaanxi), sailed along the Mian River to Quren County (朐忍縣; west of present-day Yunyang County, Chongqing), and arrived at Xinfeng County (新豐縣; south of present-day Weinan, Shaanxi). They made camp at Dankou (丹口) but were forced to retreat due to heavy rains.
The following year, Shu forces led by Zhuge Liang attacked Tianshui Commandery and besieged Wei forces led by Jia Si (賈嗣) and Wei Ping (魏平) at Mount Qi (祁山; the mountainous regions around present-day Li County, Gansu). Cao Rui ordered Sima Yi to move to Chang'an (present-day Xi'an, Shaanxi) to supervise military operations in Yong and Liang provinces. After making preparations for battle, Sima Yi, with Zhang He, Fei Yao, Dai Ling (戴陵) and Guo Huai serving as his subordinates, led the Wei forces to Yumi County (隃麋縣; east of present-day Qianyang County, Shaanxi) and stationed there.
When Zhuge Liang heard of the Wei army's arrival, he led his troops to Shanggui County (上邽縣; in present-day Tianshui, Gansu) to collect the harvest. In response, Sima Yi led his troops to Shanggui County and reached there within two days. By then, Zhuge Liang and his men had finished harvesting the wheat in Shanggui County, and they retreated when they learnt that Sima Yi was heading there. Sima Yi encountered Zhuge Liang at Hanyang (漢陽), where he ordered his troops to get into formation, while at the same time sending Niu Jin to lead a lightly-armed cavalry detachment to lure the enemy to Mount Qi. Zhuge Liang and his troops garrisoned at Lucheng (鹵城), took control of the hills in the north and south, and used the river as a natural barrier.
Although his subordinates repeatedly urged him to attack the enemy, Sima Yi was hesitant to do so after seeing the layout of the Shu camps in the hills. However, he eventually relented when his subordinates mocked him and said he would become a laughing stock if he refused to attack. Sima Yi sent Zhang He to attack the Shu camp in the south, guarded by Wang Ping, while he led the others to attack Lucheng head-on. In response, Zhuge Liang ordered Wei Yan, Wu Ban and Gao Xiang to lead troops to engage the enemy outside Lucheng. The Wei army lost the battle, along with 3,000 troops and some equipment.
Despite his victory, Zhuge Liang could not make use of the momentum to launch a major offensive on the enemy because his army was running low on supplies. Sima Yi launched another attack on the Shu camps and succeeded in breaking through Zhuge Liang's defences. The Book of Jin mentioned that as Zhuge Liang and the Shu army retreated under the cover of night, Sima Yi led his forces in pursuit and inflicted over 10,000 casualties on the enemy. Cao Rui sent an emissary to congratulate Sima Yi on his victory and rewarded him by adding more taxable households to his marquisate.
Du Xi and Xue Ti (薛悌) told Sima Yi that the wheat will be ready for harvest the following year and Zhuge Liang would definitely come to seize the wheat. Since Longyou (隴右) lacked food supplies, they should transport the wheat there that winter. Sima Yi said, "Zhuge Liang advanced towards Mount Qi again and attacked Chencang (陳倉; east of present-day Baoji, Shaanxi) but lost and withdrew. If he advances again, instead of attacking cities, he'll call for a battle in the east of Long(you) and not the west. Zhuge Liang feels frustrated by the shortage of grain so he'll definitely stockpile supplies when he returns (to Shu). Based on my prediction, he won't attack again if he doesn't have at least three harvests' worth of food supplies." Sima Yi then proposed to the Wei imperial court to mobilise farmers from Ji Province to Shanggui County and put them under the jurisdiction of Jingzhao (京兆), Tianshui and Nan'an (南安) commanderies. By 233, Sima Yi's agricultural plan came to fruition and became a source of food supplies for the three commanderies.
In 234, Zhuge Liang led more than 100,000 Shu troops out of the Xie Valley (斜谷) and camped at the southern bank of the Wei River near Mei County (郿縣; southeast of present-day Fufeng County, Shaanxi). The Wei emperor Cao Rui became worried so he ordered Qin Lang to lead 20,000 infantry and cavalry as reinforcements to join Sima Yi. Zhuge Liang later moved his army west to the Wuzhang Plains and prepared to cross to the northern bank of the Wei River. Sima Yi sent Zhou Dang (周當) to station at Yangsui (陽遂) and lure Zhuge Liang to attack him. When Zhuge Liang made no response, Sima Yi sent Hu Zun (胡遵) and Guo Huai to lead troops to join Zhou Dang at Yangsui. They encountered the Shu forces near the Wuzhang Plains and fought a skirmish before the Shu forces retreated back to the plains. One night, Sima Yi saw a star falling towards the Shu camp and predicted that Zhuge Liang would be defeated. He ordered a surprise attack on the Shu camp from behind: 500 Shu soldiers were killed, 600 surrendered, and more than 1,000 livestock of the Shu army were captured by Wei forces.
Around the time, the Wei government observed that since the Shu army was far away from its base at Hanzhong Commandery, it would not be in its interest to fight a prolonged war in enemy territory, so it would be better for the Wei army to adopt a defensive posture against the Shu invaders. The Wei emperor Cao Rui thus ordered Sima Yi to hold his position and refrain from engaging the Shu forces in battle. Zhuge Liang attempted to lure Sima Yi to attack him; on one occasion, Zhuge Liang sent Sima Yi women's ornaments to taunt him. Sima Yi, apparently feeling enraged, sought permission from Cao Rui to attack the enemy, but was denied. The emperor even sent Xin Pi, bearing the imperial scepter (a symbol of the emperor's authority), to the battlefield to make sure that Sima Yi followed orders and remained in camp. Zhuge Liang knew that Sima Yi was pretending to be angry because he wanted to show the Wei soldiers that he would not put up with the enemy's taunting, and to ensure that the Wei soldiers were ready for battle.
After a standoff lasting more than 100 days, Sima Yi heard from civilians that Zhuge Liang had died from illness and the Shu army had burnt down their camp and retreated. He then led his troops to pursue the enemy and caught up with them, but retreated when the Shu forces got into battle formation. Some days later, Sima Yi surveyed the remains of the Shu camp and concluded that Zhuge Liang was indeed dead when he saw that the Shu army had hastily retreated, so he led his troops in pursuit again. When Sima Yi reached Chi'an (赤岸), he asked the civilians living there about Zhuge Liang and heard that there was a saying: "A dead Zhuge (Liang) scares away a living Zhongda[d]" When Sima Yi heard that, he laughed and said, "I can predict the thoughts of the living but I can't predict the dead's."
In 235, Sima Yi was promoted to Grand Commandant (太尉) and had the number of taxable households in his marquisate increased. In the same year, when the Shu general Ma Dai led troops to invade Wei, Sima Yi sent Niu Jin to lead Wei forces to resist the invaders. Niu Jin defeated Ma Dai and killed more than 1,000 enemy soldiers. When a famine broke out in Guandong (關東; referring to the area east of Hangu Pass), Sima Yi had more than five million hu of grain transported from Chang'an to Luoyang to aid in disaster relief efforts.
In 236, Sima Yi caught a white deer, which was regarded as an auspicious animal, and presented it to the Wei emperor Cao Rui. Cao Rui said, "When the Duke of Zhou assisted King Cheng in governance, he presented white pheasants to the king. Now you're in charge of Shaanxi and you present a white deer. Isn't this a sign of loyalty, cooperation, long-lasting stability and peace?"
Around the same time, Gongsun Yuan, a warlord based in Liaodong Commandery (in present-day Liaoning) who previously pledged allegiance to the Cao Wei state, started a rebellion and declared independence. Cao Rui summoned Sima Yi back to the imperial capital Luoyang to consult him on how to deal with the Liaodong crisis. Sima Yi said that he needed only one year to lead troops to Liaodong to suppress the revolt. At the time, the Wei government had forced many men into military service or recruited them for manual labour to work on Cao Rui's palace construction/renovation projects. Sima Yi felt that doing so would increase the burden on the common people and make them resent the Wei government, so he advised Cao Rui to halt the projects and focus on dealing with the more pressing issues.
In 238, Sima Yi led an army of 40,000 from Luoyang to attack Liaodong, with Niu Jin and Hu Zun (胡遵) serving as his subordinates. Cao Rui personally saw them off from Luoyang. The Wei army reached Liaodong in June 238 and suppressed the revolt by September. Gongsun Yuan was killed in battle near the Liang River outside Xiangping (襄平; present-day Liaoyang, Liaoning), the capital of Liaodong Commandery. After his army occupied Xiangping, Sima Yi ordered a systematic purge of some 7,000 men aged 14 and above in the city, as well as the execution of Gongsun Yuan's subjects and their families (numbering over 2,000 people). In total, he gained control over 40,000 households and 300,000 livestock in Xiangping. Sima Yi also posthumously rehabilitated Lun Zhi (倫直) and Jia Fan (賈範), two officials who attempted to stop Gongsun Yuan from rebelling but were executed by him, and freed Gongsun Gong, the previous Administrator of Liaodong who had been imprisoned by his nephew Gongsun Yuan.
At the time, as it was in winter, many soldiers were suffering from the cold and wanted extra clothing to keep themselves warm. When someone pointed out that they had a surplus of ru (襦; a type of clothing) and suggested giving them out to the soldiers, Sima Yi said, "The rus are the property of the government. No one is allowed to give them to others without permission." Sima Yi also wrote to the Wei imperial court to seek permission for soldiers aged 59 and above to retire from service and for the dead and wounded to be sent home. As Sima Yi led the troops back to Luoyang from Liaodong, Cao Rui sent an emissary to meet them in Ji County (薊縣; in present-day Beijing) and host a party to celebrate the victory. He also added Kunyang County (昆陽縣; present-day Ye County, Henan) to Sima Yi's marquisate, so Sima Yi had a total of two counties as his marquisate.
When Sima Yi was away on the Liaodong campaign, he once dreamt that Cao Rui wanted to see him and he sensed that something was wrong. Later, Cao Rui issued an imperial order instructing him to return to Luoyang via a faster route through the Guanzhong region. When Sima Yi reached Baiwu (白屋), he received another five orders within three days. Sensing the urgency of the situation, he boarded a zhuifengche (追鋒車)[e] and travelled overnight across the Baiwu region over a distance of more than 400 li and reached Luoyang by the following day. He met Cao Rui at Jiafu Hall (嘉福殿) of the imperial palace and saw that the emperor was critically ill. With tears in his eyes, Sima Yi asked Cao Rui about his condition. Cao Rui held Sima Yi's hand, looked at his adopted son Cao Fang, and told Sima Yi, "I have matters to entrust you. Now that I meet you one last time before I die, I have no more regrets." He then designated Sima Yi and the general Cao Shuang as the regents for Cao Fang because Cao Fang was still very young at the time.
Before his death, Cao Rui had initially planned to exclude Sima Yi from the regency and instead appoint Cao Yu, Xiahou Xian (夏侯獻), Cao Shuang, Cao Zhao and Qin Lang as the regents. However, two of his close aides, Liu Fang and Sun Zi, who were not on good terms with Xiahou Xian and Cao Zhao, managed to persuade him to exclude those two and appoint Cao Shuang and Sima Yi as the regents instead.
In February 240, when a seven-year-old Cao Fang started ruling as the new Wei emperor, the Wei government appointed Sima Yi as a Palace Attendant (侍中) and Manager of the Affairs of the Masters of Writing (錄尚書事), granted him imperial authority, and ordered him to oversee military affairs within and outside the imperial capital Luoyang. Sima Yi and Cao Shuang each held command over 3,000 troops and served as regents for the underage emperor. As Cao Shuang wanted the Masters of Writing (i.e. the Imperial Secretariat) to report to him first, he proposed to the imperial court to reassign Sima Yi to be the Grand Marshal (大司馬). As the persons who previously held the position of Grand Marshal all died in office, the imperial court thought that it would be more appropriate to appoint Sima Yi as Grand Tutor (太傅) instead. Sima Yi was also awarded additional privileges similar to those granted to Xiao He in the early Western Han dynasty and Cao Cao in the late Eastern Han dynasty: He did not have to walk briskly when he entered the imperial court, did not have to have his name announced when he entered, and was allowed to wear shoes and carry a sword into the imperial court. His eldest son, Sima Shi, was appointed as a Regular Mounted Attendant (散騎常侍), while three of his relatives were enfeoffed as marquises and four others were appointed as Cavalry Commandants (騎都尉). Sima Yi ordered his relatives to decline the honours and appointments.
In the spring of 239, the Wa, Karasahr, Weixu (危須) states and the Xianbei tribes living south of the Ruo River came to pay tribute to the Cao Wei state. Cao Fang attributed this to the efforts of his subjects and he rewarded Sima Yi by increasing the number of taxable households in his marquisate. Sima Yi also suggested that the Wei imperial court put an end to the extravagant palace construction/renovation projects started in Cao Rui's reign, and divert those resources and manpower towards agriculture instead. The imperial court approved.
Around late May or June 241, Wei's rival state Eastern Wu launched an invasion of Wei on three fronts: Quebei (芍陂; south of present-day Shou County, Anhui), Fancheng (樊城; present-day Fancheng District, Xiangyang, Hubei), and Zhazhong (柤中; west of present-day Nanzhang County, Hubei). When Sima Yi requested to lead troops to resist the enemy, there were other officials in the imperial court who argued that there was no need to take swift action since Fancheng was strong enough to withstand attacks and that the enemy was weary after travelling a long distance. Sima Yi disagreed and pointed out that the Wu invasion posed a huge threat to Wei. He knew that if Fancheng fell to the enemy, it would put Wei in a dangerous situation.
In late June or July 241, Sima Yi led an army from Luoyang to fight the Wu invaders. He first sent lightly-armed cavalry to harass the Wu forces while his main army remained in position. Later, he ordered his troops to pretend to put up an offensive stance to intimidate the enemy into retreating. The Wu forces fell for the ruse and retreated overnight. Sima Yi and the Wei forces pursued the retreating Wu forces to the intersection of the Han, Bai and Tang rivers, where they defeated and killed over 10,000 enemy soldiers and captured their boats, equipment and other resources. Cao Fang sent a Palace Attendant as an emissary to meet Sima Yi at Wan (宛; in present-day Nanyang, Henan) to congratulate him and host a banquet to celebrate the victory.
In August 241, the Wei imperial court added Yan (郾) and Linying (臨潁) counties to Sima Yi's marquisate as a reward for his contributions; at the time, Sima Yi's marquisate spanned four counties and covered 10,000 taxable households. 11 of Sima Yi's relatives were also enfeoffed as marquises. As Sima Yi gained greater glory for his achievements, he behaved in a more humble and modest manner. For example, whenever he met Chang Lin (常林), who was from the same hometown as him and held the position of Minister of Ceremonies in the Wei imperial court, he bowed to him in a respectful manner. He also constantly reminded his siblings, children and younger relatives to be mindful of their conduct. In the spring of 242, Cao Fang bestowed the posthumous title "Marquis Cheng of Wuyang" (舞陽成侯) upon Sima Yi's deceased father, Sima Fang.
In April or May 242, Sima Yi proposed to the Wei government to dig a canal to connect the Yellow and Bian rivers and direct their waters towards the southeast to promote agriculture in the areas north of the Huai River.
At the time, Zhuge Ke, a general from Wei's rival state Wu, was stationed at a military garrison at Wan (皖; present-day Qianshan County, Anhui) and posed a threat to the Wei forces in the region. When Sima Yi wanted to lead troops to attack Zhuge Ke, many officials advised him against it. They said that Wan was heavily fortified and abundant in supplies and that Wu reinforcements would come to Zhuge Ke's aid if he came under attack, thus putting the invaders in a perilous position. Sima Yi disagreed and said, "The enemy is adept at naval warfare. Why don't we try attacking their land garrison and see what happens. If they know their strengths, they will abandon the garrison and retreat; this is our objective. If they hold up inside the garrison and defend their position, their reinforcements will have to reach them via land because the waters are too shallow in winter for boats to sail through. In doing so, they will be putting themselves at a disadvantage because they aren't as good in land-based warfare as us."
In October 243, Sima Yi led an army from Luoyang to attack Zhuge Ke at Wan. When Sima Yi and his army reached Shu County (舒縣; present-day Shucheng County, Anhui), Zhuge Ke gave orders to burn down all the supplies stockpiled in Wan, abandon the garrison and retreat. Sima Yi's aim was to destroy the Wu forces' sources of food supply in the Huai River region, so once Zhuge Ke burnt down all the supplies in Wan, Sima Yi felt more at ease. He then implemented the tuntian policy and large-scale agricultural and irrigation works in the region. In late January or February 244, Cao Fang sent an emissary to meet Sima Yi at Huainan Commandery (淮南郡; around present-day Shou County, Anhui) and honour him for his achievements in promoting agriculture in the region.
In 244, the officials Deng Yang and Li Sheng advised Cao Shuang to launch a military campaign against Wei's rival state Shu to boost his fame and authority in Wei. Sima Yi strongly objected to this idea but Cao Shuang ignored him and proceeded with the campaign. He suffered a defeat at the Battle of Xingshi in April 244 against Shu forces.
In September 245, Cao Shuang wanted to make changes to the structure of the military so that he could put his brothers Cao Xi (曹羲) and Cao Xun (曹訓) in command of troops. Sima Yi opposed these changes but Cao Shuang ignored him and went ahead. In January 246, the Wei emperor Cao Fang granted Sima Yi the privilege of riding to the imperial court in a type of horse-drawn carriage traditionally reserved for emperors.
In February 246, when Eastern Wu forces attacked Zhazhong (柤中; west of present-day Nanzhang County, Hubei), over 10,000 households living in the area fled to the north across the Mian River (沔水). When news of the Wu invasion reached the Wei imperial court, Sima Yi argued that they should let the civilians remain on the north side of the Mian River since the south side was near enemy territory and hence too dangerous for them. However, Cao Shuang said, "It isn't in our long-term interests to allow the civilians to remain here and give up trying to secure the south of the Mian River." Sima Yi disagreed and said, "If the enemy sends 20,000 troops to cut off passage across the Mian River, sends another 30,000 troops to fight our forces at the south of the Mian River, and sends another 10,000 troops to occupy Zhazhong, what can we do to save those civilians?" Cao Shuang refused and ordered the refugees to return to the south of the Mian River. As Sima Yi foresaw, the Wu forces occupied Zhazhong, captured the civilians and relocated them to Wu territory.
Around the time, Cao Shuang wanted to dominate the Wei government so he used a series of political manoeuvres to consolidate and concentrate power in the hands of himself and his clique. He heeded the advice of his close aides He Yan, Deng Yang and Ding Mi (丁謐), and relocated Empress Dowager Guo (Cao Rui's widow) to Yongning Palace (永寧宮) so that she could not interfere in politics. He also put his brothers in command of the military, promoted his close aides to higher positions in the imperial court, and made changes to the political structure to benefit himself and his clique. Sima Yi tried to stop Cao Shuang but could not; Cao Shuang became increasingly distrustful and wary of Sima Yi. In June 246, Sima Yi claimed that he was ill and withdrew from the political scene. At the time, there was a saying in Luoyang which goes: "He (Yan), Deng (Yang) and Ding (Mi) create turmoil in the imperial capital."
In April or May 248, Zhang Dang (張當), a palace eunuch, illegally transferred 11 women out of the imperial harem and presented them to Cao Shuang to be his concubines. Cao Shuang and his close aides thought that Sima Yi was seriously ill and could no longer do anything, so they plotted with Zhang Dang to overthrow the emperor Cao Fang and put Cao Shuang on the throne. However, they were still wary of Sima Yi and did not lower their guard against him.
At the time, Li Sheng, one of Cao Shuang's supporters, had been recently reassigned to be the Inspector of Jing Province. Cao Shuang secretly instructed him to check if Sima Yi was as ill as he claimed, so Li Sheng visited Sima Yi before leaving for Jing Province. Sima Yi knew the true purpose of Li Sheng's visit, so he pretended to be frail and senile. Li Sheng saw that Sima Yi could not move around and wear clothes without help from his servants, and could not even consume congee without soiling his clothes. He then told Sima Yi, "Everyone thought that your illness was a minor one; alas, who expected you to be in such poor health?" Sima Yi pretended to cough and pant as he replied, "I'm old and sick and I'm going to die soon. When you go to Bing Province, you should be careful because it is near barbarian territory. We might not see each other again, so I entrust my sons Shi and Zhao to your care." Li Sheng said, "I'm returning to my home province, not Bing Province." Sima Yi pretended to mishear and he said, "You're going to Bing Province, aren't you?" Li Sheng then said, "My home province is Jing Province." Sima Yi replied, "I'm so old and weak that I can't even hear you. So now you're going back to your home province. It's time for you to make some glorious achievements!" Li Sheng returned to Cao Shuang and told him, "Sima Yi is dying soon and no longer of sound mind. There's nothing for you to worry about." Later, he said, "It's sad to see that the Grand Tutor is no longer in a good state of health to serve." Cao Shuang lowered his guard against Sima Yi.
On 5 February 249, Cao Shuang and his brothers accompanied the emperor Cao Fang on a visit to the Gaoping Tombs (高平陵). On that day, Sima Yi seized the opportunity to stage a coup d'état against his co-regent. He went to Yongning Palace to meet Empress Dowager Guo and ask her to remove Cao Shuang and his brothers from power. At the same time, he granted imperial authority to Gao Rou, the Minister over the Masses (司徒), appointed him as acting General-in-Chief (大將軍) and ordered him to take command of Cao Shuang's troops. He also appointed Wang Guan, the Minister Coachman (太僕), as acting Commandant of the Central Army (中領軍) and ordered him to seize command of the troops under Cao Shuang's brother Cao Xi (曹羲).
Sima Yi, along with the Grand Commandant (太尉) Jiang Ji and others, led troops out of Luoyang to the floating bridge above the Luo River, where he sent a memorial to the emperor Cao Fang, listing out Cao Shuang's "crimes" (e.g. not fulfilling his duty as regent, corrupting the government, conspiring with Zhang Dang) and requesting the emperor to remove Cao Shuang and his brothers from their positions of power. Cao Shuang ultimately surrendered to Sima Yi and gave up his powers, thinking that he could still lead a luxurious life in retirement.
After returning to Luoyang, Cao Shuang was accused of plotting treason with the palace eunuch Zhang Dang (張當) and was arrested along with his brothers and his supporters, including He Yan, Ding Mi (丁謐), Deng Yang, Bi Gui, Li Sheng and Huan Fan. They were subsequently executed along with the rest of their families and relatives. Jiang Ji had attempted to persuade Sima Yi to spare Cao Shuang and his brothers in consideration of the meritorious service rendered by their father Cao Zhen, but Sima Yi refused.
In March 249, Cao Fang appointed Sima Yi as Imperial Chancellor (丞相) and added another four counties – Fanchang (繁昌), Yanling (鄢陵), Xinji (新汲) and Fucheng (父城) – to Sima Yi's marquisate, bringing the size of the marquisate to a total of eight counties and 20,000 taxable households. Cao Fang also awarded Sima Yi the privilege of not having to announce his name when he spoke to the emperor. Sima Yi declined the appointment of Imperial Chancellor. In January 250, Cao Fang awarded Sima Yi the nine bestowments and an additional privilege of not having to kowtow during imperial court sessions. Sima Yi declined the nine bestowments. In February or March 250, Cao Fang had an ancestral shrine built for the Sima family in Luoyang, increased the size of Sima Yi's personal staff, promoted some of Sima Yi's personal staff, and enfeoffed Sima Yi's sons Sima Rong (司馬肜) and Sima Lun as village marquises. At the time, as Sima Yi was chronically ill, he could not regularly attend imperial court sessions, so Cao Fang often visited him as his residence to consult him on policy matters.
Wang Ling, the Grand Commandant (太尉), and his nephew Linghu Yu (令狐愚), the Inspector of Yan Province, became worried of Sima Yi's growing influence over the emperor Cao Fang, so they plotted to overthrow Sima Yi and replace Cao Fang with Cao Biao, the Prince of Chu.
In February 251, Wang Ling lied that Eastern Wu forces were approaching Tushui (塗水) and requested that the Wei government give him troops to resist the invaders. Sima Yi knew that Wang Ling was lying so he refused to approve the request. In May 251, Sima Yi personally led an army towards Wang Ling's position and reached Gancheng (甘城) within nine days. Wang Ling knew that Sima Yi already knew about his plans to rebel, so he decided to surrender. He tied himself up and met Sima Yi at Wuqiu (武丘) and told him, "If I'm guilty, you can summon me to meet you. Why do you need to come here?" Sima Yi replied, "That's because you're not someone who responds to summons." Wang Ling was then escorted as a prisoner back to Luoyang. Along the way, when he passed by a shrine honouring the Wei general Jia Kui, he exclaimed, "Jia Liangdao! Wang Ling is a loyal subject of Wei. Only the gods know if this is true." He later committed suicide by consuming poison at Xiang County (項縣; present-day Shenqiu County, Henan). Sima Yi had Wang Ling's conspirators arrested and executed along with their families; even Cao Biao was forced to commit suicide. He then relocated the other nobles from the Cao family to Ye city, where they were effectively put under house arrest there.
Cao Fang sent Wei Dan (韋誕) as an emissary to meet Sima Yi at Wuchi (五池) and congratulate him on his success in suppressing Wang Ling's rebellion. Later, when Sima Yi reached Gancheng, Cao Fang sent Yu Ni (庾嶷) as an emissary to appoint Sima Yi as Chancellor of State (相國) and promote him from a marquis to a duke under the title "Duke of Anping Commandery" (安平郡公). One of Sima Yi's grandsons and one of his brothers were also enfeoffed as marquises. At the time, the Sima family had a total of 19 marquises and 50,000 taxable households in all their marquisates combined. Sima Yi declined the appointment of Chancellor of State and refused to accept his enfeoffment as a duke.
In July 251, when Sima Yi became critically ill, he dreamt of Jia Kui and Wang Ling being honoured, and he felt disturbed after that. He died on 7 September 251 in Luoyang at the age of 73 (by East Asian age reckoning). The emperor Cao Fang donned mourning garments, attended Sima Yi's funeral in person, and even ordered Sima Yi to be buried with the same honours as those accorded to Huo Guang in the Western Han dynasty. He also posthumously appointed Sima Yi as Chancellor of State (相國) and posthumously elevated him to the status of a duke. However, Sima Yi's younger brother Sima Fu declined the ducal title and a wenliangche (轀輬車)[f] on behalf of his deceased brother, stating that Sima Yi would have done that if he were still alive.
Sima Yi was buried on 19 October 251 at Heyin County (河陰縣; north of present-day Mengjin County, Henan). Cao Fang granted him the posthumous title "Wenzhen" (文貞), which was later changed to "Wenxuan" (文宣). However, before his death, Sima Yi had made arrangements to be buried at Mount Shouyang (首陽山; in present-day Yanshi, Luoyang, Henan) with no markers (e.g. tombstone, trees) around his tomb, to be dressed in plain clothes, and have no luxury items buried with him. He also made a rule stating that his family members who died after him should not be buried with him.
In 264, after the Wei emperor Cao Huan enfeoffed Sima Yi's second son Sima Zhao as the vassal King of Jin (晉王), Sima Zhao honoured his father the posthumous title "King Xuan" (宣王). One year later, after Sima Yi's grandson Sima Yan (Emperor Wu) usurped the throne from Cao Huan and established the Jin dynasty (265–420) with himself as the emperor, he honoured his grandfather with the posthumous title "Emperor Xuan" (宣皇帝) with the temple name "Gaozu" (高祖), and named his grandfather's burial place "Gaoyuan Mausoleum" (高原陵).
In his younger days, Sima Yi was a close friend of Hu Zhao (胡昭). In one incident, Zhou Sheng (周生) kidnapped Sima Yi and wanted to kill him. Hu Zhao braved danger to meet Zhou Sheng in the Xiao Mountains and tried to persuade him to let Sima Yi go. When Zhou Sheng refused, Hu Zhao cried and pleaded with him. Zhou Sheng was so moved by Hu Zhao's sincerity that he released Sima Yi. As Hu Zhao never told anyone about this incident, very few people knew that Sima Yi owed him his life.
Cao Cao heard that Sima Yi was not only ambitious, but also had a lang gu (狼顧)[g] appearance, so he wanted to test and see if it was true. One day, he ordered Sima Yi to walk in front of him and then made him look back. Sima Yi purportedly turned his head 180 degrees to look back. Cao Cao also once dreamt of three horses feeding from the same trough[h] and he felt disturbed, so he warned Cao Pi: "Sima Yi won't be content with being a subject; he will interfere in your family matters." As Cao Pi was on good terms with Sima Yi, he often protected and shielded Sima Yi from criticisms. Sima Yi also took great care to create an image of himself as a diligent and faithful subject in front of Cao Cao to reduce the latter's suspicions of him.
Cao Hong, a veteran general serving under Cao Cao, had heard of Sima Yi's talent and wanted to recruit him as an adviser. However, as Sima Yi disliked Cao Hong, he refused to meet him and pretended to be so ill that he could not move around without using crutches. Cao Hong was so unhappy that he reported it to Cao Cao, who then summoned Sima Yi. When Sima Yi heard that Cao Cao wanted to meet him, he immediately threw aside his crutches and rushed there.
The Tang dynasty historian Fang Xuanling, who was the lead editor of Sima Yi's biography in the Book of Jin, noted that Sima Yi was known for appearing to be generous and magnanimous on the outside while being distrustful and jealous on the inside. He wrote that Sima Yi was suspicious, calculative, manipulative and adept in politics, and pointed out Sima Yi's cruelty in his massacre of Liaodong's population and his extermination of Cao Shuang and his entire clan.
In 238, when Gongsun Yuan heard that Sima Yi was leading a Wei army to Liaodong to attack him, he sent a messenger to request reinforcements from Wei's rival state, Eastern Wu. The Wu emperor Sun Quan initially wanted to send reinforcements and he wrote to Gongsun Yuan: "Sima Yi is well-versed in military arts. He uses military strategy like a god. He defeats all who stand in his way. I'm deeply worried for you, my brother."
The Eastern Jin dynasty's Emperor Ming (r. 323–325), a descendant of Sima Yi, once asked an official Wang Dao to tell him about the origins of the Jin dynasty, so Wang Dao told him everything from Sima Yi's career to Cao Mao's attempted coup against Sima Zhao. After hearing from Wang Dao, Emperor Ming remarked, "If what you said is true, how can the Jin (dynasty) expect to last long?"
After the fall of the Western Jin dynasty in 316, the belief began to shift from the popular ideal that the Cao Wei state was the rightful successor to the Han dynasty towards the alternative view that the Shu Han state had greater legitimacy. Before 316, Sima Yi was seen as a righteous figure and was practically deified; after 316, however, he became a vilified figure in Chinese culture.
Sima Yi is a major character in the 14th-century historical novel Romance of the Three Kingdoms, which romanticises the historical figures and events before and during the Three Kingdoms period of China. In the novel, he is cast as a villainous figure who pretends to be a loyal and dedicated subject of the Cao Wei state, while secretly planning to concentrate power in his hands and pave the way for his descendants to usurp the throne one day – in the same way Cao Cao did towards the end of the Eastern Han dynasty. He also serves as a nemesis to Zhuge Liang during the Shu invasions of Wei between 228 and 234, with both of them trying to outwit each other in the various battles.
The various accounts contributing to the portrayal of Sima Yi as a villain, however, are neither historically accurate nor consistent with each other. They were most likely borrowed or adapted from the historical novel Romance of the Three Kingdoms, as well as folktales and legends about Sima Yi passed down through the ages.
Sima Yi also appears as a playable character in Koei's Dynasty Warriors and Warriors Orochi video game series. In the mobile game Puzzles & Dragons, he is featured as a God type in their Three Kingdoms 2 Pantheon alongside Ma Chao and Diaochan. In the collectible card game Magic: The Gathering there is a card named "Sima Yi, Wei Field Marshal" in the Portal Three Kingdoms set.
Notable actors who have portrayed Sima Yi on screen include: Wei Zongwan, in Romance of the Three Kingdoms (1994); Ni Dahong, in Three Kingdoms (2010); Eric Li, in Three Kingdoms RPG (2012); Wu Xiubo, in The Advisors Alliance (2017); and Elvis Han, in Secret of the Three Kingdoms (upcoming).
Media related to Sima Yi at Wikimedia Commons