The Political Landscape of Late Cao Wei

In the twilight years of Cao Wei’s dominance during the Three Kingdoms period, a pivotal power struggle emerged between regent Cao Shuang and veteran statesman Sima Yi. Following Emperor Cao Rui’s death in 239, the young Emperor Cao Fang inherited the throne, with Cao Shuang—a distant relative of the imperial clan—and Sima Yi appointed as co-regents. This arrangement set the stage for an escalating confrontation that would ultimately determine the fate of the Wei dynasty.

Cao Shuang quickly consolidated power by securing two critical positions: control over the Imperial Secretariat (录尚书事) and command of the palace guards. Simultaneously, he surrounded himself with controversial figures like He Yan, Deng Yang, Li Sheng, and Ding Mi—intellectuals previously marginalized during Cao Rui’s reign. These appointments reflected Cao Shuang’s strategy to build a loyal faction while systematically excluding Sima Yi from decision-making.

The Systematic Marginalization of Sima Yi

The political chess game began in earnest when Cao Shuang engineered Sima Yi’s “promotion” to the honorary position of Grand Tutor in 239, effectively removing his rival from military command and administrative authority. Remarkably, Sima Yi initially accepted this demotion without protest, even refusing compensatory honors—a tactical retreat that masked his long-term strategy.

Meanwhile, Cao Shuang’s faction assumed key government roles:
– He Yan controlled official appointments as Minister of Personnel
– Li Sheng became Governor of Henan
– Bi Gui served as Colonel-Director of Retainers with judicial oversight

Military appointments proved more sensitive. After briefly appointing Bi Gui as Central Protector of the Army, Cao Shuang replaced him with his cousin Xiahou Xuan—demonstrating his preference for familial loyalty over meritocracy in critical security positions.

Sima Yi’s Calculated Countermoves

While appearing politically neutered, Sima Yi continued contributing to state affairs. His 243 campaign against Eastern Wu’s Zhuge Ke—though inconclusive—allowed him to implement agricultural reforms along the Huai River. Establishing military colonies (屯田) that connected Shouchun to Luoyang, these economic initiatives mirrored Zhuge Liang’s policies in Shu Han, earning Sima Yi public admiration as “Wei’s Zhuge Liang.”

A pivotal moment came in 244 when veteran official Zhao Yan resigned from governing the strategic Guanzhong region. Cao Shuang appointed Xiahou Xuan as replacement, creating a vacancy in the Central Protector position. Through backchannel negotiations (likely offering support for Xiahou Xuan’s inexperienced administration), Sima Yi secured the post for his eldest son Sima Shi—planting a crucial ally within the palace guard system.

Cao Shuang’s Fatal Miscalculations

Emboldened by his political dominance, Cao Shuang pursued military glory through a 244 invasion of Shu Han. Despite warnings about Sichuan’s natural defenses and Shu’s capable leadership (Jiang Wan and Fei Yi maintaining Zhuge Liang’s legacy), the campaign ended disastrously. Wei forces under Xiahou Xuan were repelled by Shu general Wang Ping at Xingshi, suffering heavy casualties during their retreat.

This military debacle damaged Cao Shuang’s credibility while Sima Yi’s faction quietly strengthened. Between 245-247, Cao Shuang made several critical errors:
1. Consolidating palace guard units under his brother Cao Xi, eliminating checks on his power
2. Forcibly relocating Empress Dowager Guo (a potential ally for Sima Yi) from the palace
3. Allowing his faction’s corruption to alienate veteran officials

The Gathering Storm of Opposition

By 248, resentment against Cao Shuang’s regime reached a boiling point. Veteran officials like Sun Li, Jiang Ji, and the influential Taiwei Rui Ji publicly criticized his administration’s excesses. Meanwhile, Sima Shi—during his tenure as Central Protector (244-247)—had secretly cultivated a network of 3,000 loyalists among lower-ranking officers, offering merit-based promotions to create a dependable power base.

When Cao Shuang sent Li Sheng to assess the supposedly ailing Sima Yi in 248, the elderly statesman delivered an Oscar-worthy performance—feigning senility by spilling porridge and mishearing questions. This theatrical deception convinced Cao Shuang that his rival posed no threat.

The Coup of 249: Gaoping Tombs Incident

The final act unfolded in February 249 when Cao Shuang and his brothers accompanied Emperor Cao Fang to visit the Gaoping Tombs. Seizing this opportunity, Sima Yi:
1. Secured Empress Dowager Guo’s edict condemning Cao Shuang
2. Closed Luoyang’s gates using Sima Shi’s hidden forces
3. Gained support from disgruntled officials like Jiang Ji

Despite holding the emperor hostage outside the city, Cao Shuang surrendered after Jiang Ji famously promised his safety “on the Luo River’s waters.” The subsequent purge eliminated Cao Shuang’s faction, with He Yan, Deng Yang, and others executed along with their clans—marking the Sima clan’s irreversible ascendancy.

Legacy: From Wei to Jin

This power struggle’s consequences reverberated through Chinese history:
1. It destroyed the Cao-Wei imperial clan’s authority, paving way for the Jin dynasty
2. Established the “usurper’s playbook” later employed by warlords
3. Demonstrated how meritocratic military appointments could overthrow nepotistic regimes

Sima Yi’s victory wasn’t merely personal ambition—it reflected broader dissatisfaction with Cao Shuang’s corrupt, exclusionary governance. The episode remains a timeless study in political patience, the dangers of unchecked power, and how seemingly minor personnel decisions (like Sima Shi’s appointment) can alter empires.