Deng Ai (197 – late March 264[3]), courtesy name Shizai, was a Chinese military general and politician of the state of Wei during the Three Kingdoms period of China.

By leading a strike force through a shortcut across dangerous mountainous terrain, Deng Ai showed up in the vicinity of the Shu capital, Chengdu, and took the enemy by surprise.

He read two lines engraved on Chen Shi's tombstone: "his writings became examples of excellent prose; his conduct served as a role model for scholar-officials" (文為世範，行為士則).

[Sanguozhi zhu 1] Sometime between 235 and 239,[c] he was sent as a messenger to the capital, Luoyang, where, by chance, he met Sima Yi, who was then serving as the Grand Commandant (太尉) under the Wei government.

Deng Ai wrote a proposal, the Ji He Lun (濟河論; Discussion on the River), to explain his ideas:[Sanguozhi 4] "The tuntian system started when the Yellow Turban Rebellion broke out.

[Sanguozhi 7] Deng Ai later became a military adviser to the Wei general Xiahou Xuan and served as the Administrator of Nan'an Commandery (南安郡; around present-day Longxi and Wushan counties, Gansu).

"[Sanguozhi 8] Guo Huai then ordered Chen Tai, Xu Zhi and Deng Ai to lead Wei forces to attack the fortresses at Qushan and cut off their food and water supplies.

Jiang Wei led his troops from Mount Niutou (牛頭山; west of present-day Zhaohua District, Guangyuan, Sichuan) to reinforce the fortresses.

For his achievements, Deng Ai was enfeoffed as a Secondary Marquis (關內侯), awarded the rank of General Who Attacks Rebels (討寇將軍), and subsequently appointed as the Administrator of Chengyang Commandery (城陽郡; around present-day Zhucheng, Shandong).

"[Sanguozhi 11]Deng Ai also suggested: "We should gradually segregate those Han Chinese living with barbarians, inculcate moral values such as integrity in them, so as to prevent them from resorting to unlawful actions."

He then sent Zhuge Xu to attack the remaining rebels and Wu forces at Lijiang Village (黎漿亭; southeast of present-day Shou County, Anhui), where they defeated the enemy.

The Wei imperial court appointed Deng Ai as General Who Stabilises the West (安西將軍) and Colonel Who Protects the Eastern Qiang (護東羌校尉) to lead troops to lift the siege.

Jiang Wei retreated to Dong Village (董亭; south of present-day Wushan County, Gansu), while Deng Ai stationed his troops at Mount Wucheng (武城山).

"[Sanguozhi 24]In the following year, Jiang Wei advanced to the Mang river in his attempt to attack the position of Deng Ai and Sima Wang.

Sima Zhao, who oversaw the campaign, ordered Deng Ai to lead 30,000 troops[Sanguozhi 26] to Tazhong (沓中; northwest of present-day Zhugqu County, Gansu) to harass Jiang Wei and keep him occupied, while Zhuge Xu, the Inspector of Yong Province, would lead forces to block Jiang Wei's retreat route back to Shu.

Some time between 18 November and 17 December 263,[d] Deng Ai led a strike force from Yinping through the shortcut, bypassing the west of Jiange and heading straight towards Jiangyou.

Deng Ai also appointed Shi Zuan as the Inspector of Yi Province and put Qian Hong in charge of overseeing the former Shu commanderies.

A memorial was constructed at Mianzhu to glorify Deng Ai's victory over Zhuge Zhan, and the fallen Wei soldiers were buried alongside their Shu counterparts.

Deng Ai wrote to Sima Zhao, suggesting that they let the weary troops rest and recuperate while concurrently making preparations for a future campaign against Wei's other rival state, Wu.

I suggest we leave 20,000 troops in Longyou (隴右) and another 20,000 in Shu to stockpile resources, build warships, and make other preparations for a future campaign against Wu.

He quoted lines from the Spring and Autumn Annals and The Art of War to hint that he was justified in ignoring standard protocol and acting autocratically as long as what he did was to Wei's benefit.

The Spring and Autumn Annals mentioned that when a general leads a campaign to a distant land, he is allowed to act in an authoritarian manner as long as his actions are beneficial to the state he serves.

"[Sanguozhi 39]Zhong Hui, Hu Lie (胡烈), Shi Zuan (師纂) and others accused Deng Ai of showing disrespect for the Wei imperial court's authority, and claimed that he was likely to start a rebellion.

[Sanguozhi zhu 2] Sometime in late February or early March 264,[2] the Wei imperial court then issued an edict ordering Deng Ai to be arrested and transported back to the capital, Luoyang.

[Sanguozhi zhu 5] After Deng Ai's death, his other son(s) in Luoyang was/were also rounded up and executed, while his surviving family members were exiled to the Western Regions.

[Sanguozhi zhu 6] In February 266, after the Jin dynasty replaced the Wei regime, Sima Yan (Emperor Wu) issued an imperial edict to pardon Deng Ai's descendants and allow them to return from exile.

Deng Ai's surviving family members were exiled and allowed to return only in 266 after Emperor Wu of the Jin dynasty issued an imperial edict pardoning them.

During the Yongjia era (307–313) in the reign of Emperor Huai, Deng Lang was appointed as the Administrator of Xindu Commandery (新都郡; around present-day Guanghan, Sichuan).

Duan Zhuo also compared Deng Ai to Bai Qi and Wu Zixu, two generals in the Spring and Autumn period who made great contributions to their respective states but were forced to commit suicide.

[Sanguozhi zhu 8] Deng Ai is first introduced as a playable character in the seventh instalment of Koei's Dynasty Warriors video game series.