[17] In 223, Cao Pi ordered Cao Zhen, Xiahou Shang, Zhang He and others to lead Wei forces to attack Wei's rival state, Eastern Wu, while he personally stationed at Wan (宛; in present-day Nanyang, Henan) to provide backup.

The Wei forces managed to defeat Wu reinforcements led by Sun Sheng (孫盛), Pan Zhang and Yang Can (楊粲), who were trying to help Zhu Ran.

During the siege, Cao Zhen ordered his troops to dig tunnels, pile up earth to form small mounds, and build watchtowers to rain arrows on the defenders in Jiangling.

[18] During the campaign, Cao Zhen and Xiahou Shang managed to destroy a Wu garrison at Niuzhu (牛渚; northwest of present-day Dangtu County, Anhui).

After he returned from the campaign, Cao Zhen was reassigned to be Senior General of the Central Army (中軍大將軍) and given an additional appointment as an Official Who Concurrently Serves in the Palace (給事中).

In Cao Pi's imperial edict, all officers holding the rank of Senior General (上將軍) with "Specially Advanced" (特進) status and below had to attend.

Zhu Shuo stood up and tried to reduce tensions by telling Wu Zhi, "His Majesty ordered you to host entertainment for everyone.

[24] In the spring of 228,[25] Zhuge Liang, the Imperial Chancellor (丞相) of Wei's rival state Shu Han, launched the first of a series of military campaigns against Wei and led the Shu forces to attack Mount Qi (祁山; the mountainous regions around present-day Li County, Gansu).

At the same time, he also ordered Zhao Yun and Deng Zhi to lead a detachment of troops to Ji Valley (箕谷) and pretend to be preparing to attack Mei County (郿縣; southeast of present-day Fufeng County, Shaanxi), so as to draw the Wei forces' attention away from Mount Qi.

At Ji Valley, Cao Zhen easily defeated Zhao Yun and Deng Zhi, who had been given command of the weaker soldiers in the Shu army.

As Cao Zhen foresaw, Zhuge Liang indeed led Shu forces to attack Chencang in the spring of 229.

However, as Hao Zhao and the Wei defenders were well-prepared, they managed to hold their ground against the second Shu invasion.

[33] In August 230, Cao Zhen led an army from Chang'an to attack Shu via the Ziwu Valley (子午谷).

At the same time, another Wei army led by Sima Yi, acting on Cao Rui's order, advanced towards Shu from Jing Province by sailing along the Han River.

The rendezvous point for Cao Zhen and Sima Yi's armies was at Nanzheng County (南鄭縣; in present-day Hanzhong, Shaanxi).

However, the campaign eventually had to be aborted in October 230[34] because the gallery roads leading into Shu were too damaged for the troops to pass through, and also because of rainy weather lasting more than 30 days.

[35] Cao Zhen fell sick on the journey back to Luoyang and became bedridden in the subsequent months.

In February 249, Sima Yi staged a coup d'état against Cao Shuang and successfully seized power from him.

Cao Zhen starts to play a more important role from Chapter 91 onwards when the Shu regent Zhuge Liang launches the Northern Expeditions against Wei.

His contributions in the series of battles against Shu are largely downplayed because the author, Luo Guanzhong, wanted to accentuate Sima Yi's resourcefulness and effectively portray him as Zhuge Liang's nemesis.

Luo Guanzhong even attributed Cao Zhen's death to his failure to heed Sima Yi's forewarning of a Shu offensive.

In Chapter 100, Sima Yi warns Cao Zhen that Shu forces will, within the next ten days, launch an attack on Mount Qi (祁山; the mountainous regions around present-day Li County, Gansu), a strategic location which would allow further incursions into the Wei heartland.

Seven days later, when his scouts report that a small number of Shu soldiers are approaching the valley, Cao Zhen sends his subordinate Qin Liang (秦良) to lead 5,000 men to survey the terrain.

Sima Yi shows up in time, drives back the Shu forces, and saves Cao Zhen.

Cao Zhen becomes so angry after reading the letter that he coughs blood and dies that night in his camp.