In February 249, he joined the regent Sima Yi in staging a successful coup d'état against his co-regent Cao Shuang, but died from illness a few months later.
Jiang Ji was from Ping'e County (平阿縣), Chu State (楚國), Yang Province, which is located north of present-day Huai'an, Anhui.
One day, Shi Miao (時苗), the magistrate of Shouchun County in Yang Province, came to the provincial office to meet Jiang Ji but the latter was drunk.
After he returned to Shouchun, he made a wooden statue, labelled it "Jiang Ji the drunkard" (酒徒蔣濟), placed it in front of a wall, and fired arrows at it day and night.
[Sanguozhi zhu 1] In 208, the warlord Sun Quan, who controlled the territories in the Jiangdong (or Wu) region, led his forces to attack Hefei, the administrative centre of Yang Province, which was guarded by the provincial governor Liu Fu.
Sun Quan saw the letters and mistakenly believed that enemy reinforcements were approaching, so he ordered his troops to burn down their camp and retreat back to Jiangdong.
In the winter of 219–220, Sun Quan ordered his general Lü Meng to lead his troops to attack the key bases of Liu Bei's territories in Jing Province: Gong'an and Jiangling counties.
[5] Cao Pi then reassigned Jiang Ji to be the Chief Clerk (長史) under Hua Xin, the Chancellor of State (相國) of his vassal kingdom at the time.
[Sanguozhi 28] When Cao Ren wanted to attack the Wu-controlled dock at Ruxu (濡須; north of present-day Wuwei County, Anhui), Jiang Ji warned him: "The enemy has occupied the west riverbank and lined up their ships on the upper stream.
When Cao Ren ignored Jiang Ji's advice and led his troops to attack Ruxu, he ended up being defeated by the Wu defenders.
[6] During this time, Jiang Ji wrote a memorial to the emperor to inform him that the harsh winter weather made it difficult for vessels to sail through the waterways into the Yangtze.
The Wu general Sun Shao seized this opportunity to send his subordinate Gao Shou (高壽) and 500 men to launch a night raid on Cao Pi's convoy.
[6] As the Wei naval fleet was stranded due to the weather, some officials proposed that the troops go ashore, break up into agricultural colonies, and start growing crops to ensure that they have adequate food supplies (i.e., the tuntian system).
Jiang Ji, however, strongly objected to this approach as he thought that it was too dangerous because the colonies would be too near the Chao Lake to the east and the Huai River to the north, so the Wu forces could take advantage of the high tide period to attack them.
By the time they reached the Jing Lake (精湖), the tide had subsided so Cao Pi left behind all the vessels for Jiang Ji to dispose of them.
"[Sanguozhi 40] At the time, Cao Xiu and his army had fallen into a Wu ambush at Shiting (石亭; near present-day Qianshan County, Anhui) and suffered heavy casualties in addition to losing weapons, armour and equipment.
[Sanguozhi 47] Once there is such a precedent, the Palace Writers will try to consolidate greater power by influencing political discourse and giving out favours to officials in exchange for their support.
When Your Majesty puts an official in multiple appointments, you should make sure that he is as loyal as the Duke of Zhou and as fair as Guan Yiwu, or else he will monopolise power and use it for corrupt purposes.
[Sanguozhi 50] As of now, there are not many officials capable of serving as pillars of the state, but there are many who are virtuous, competent, wise, loyal, faithful and hardworking enough to assume important responsibilities.
"[Sanguozhi 52] Cao Rui then promoted Jiang Ji to General Who Protects the Army (護軍將軍) and granted him an additional appointment as a Mounted Regular Attendant (散騎常侍).
"[Sanguozhi zhu 3]Cao Rui ignored Jiang Ji's advice and ordered Tian Yu to go ahead and attack Liaodong.
Jiang Ji wrote a memorial to Cao Rui as follows: "Your Majesty should continue to build on the progress made by your predecessors and expand their glorious legacy.
After his coronation, Cao Fang reassigned Jiang Ji to serve as General Who Leads the Army (領軍將軍) and enfeoffed him as the Marquis of Changling Village (昌陵亭侯).
On 1 September 242, he promoted Jiang Ji to the position of Grand Commandant (太尉)[Sanguozhi 60] to replace Man Chong, who died some months earlier.
[Sanguozhi 68] However, Jiang Ji declined the honour and wrote a memorial as follows: "I am ashamed of having been in Your Majesty's favour, while allowing Cao Shuang to harbour such traitorous thoughts.
[Sanguozhi 70] The Jin dynasty historian Sun Sheng praised Jiang Ji for showing good conscience when he declined the honour.
[Sanguozhi 71] The Shiyu (世語) recorded that during the Incident at the Gaoping Tombs, Jiang Ji wrote to Cao Shuang and promised him that Sima Yi only wanted him to give up his powers as regent.
When Cao Shuang was executed after his downfall, Jiang Ji felt so upset for failing to keep his promise that he fell sick and eventually died about three months later.
During the Xianxi era (264–265), the Cao Wei government established a new five-rank nobility system and converted Jiang Kai's peerage to the Viscount of Xiacai (下蔡子).
[Sanguozhi 72] When Jiang Ji held the position of General Who Leads the Army (領軍將軍), his wife dreamt about their deceased son crying out to her: "I am separated from you by death.