Yuan Tan (died February 205), courtesy name Xiansi, was a Chinese military general, politician, and warlord who was the eldest son of Yuan Shao, a warlord who occupied much of northern China during the late Eastern Han dynasty. After Yuan Shao's death, Yuan Tan engaged his younger brother, Yuan Shang, in a power struggle over their father's territories. He sought help from his father's rival, Cao Cao, and defeated Yuan Shang with Cao's help. However, the alliance between Yuan Tan and Cao Cao was eventually broken and Yuan was defeated and killed in the Battle of Nanpi by Cao Cao's troops.
Pacifying Qing Province
In 193, Yuan Shao appointed Yuan Tan to the position of Inspector of Qing Province, in opposition to Gongsun Zan's officer Tian Kai. Tan left Ye to station at Pingyuan; however, when he arrived Qing Province, the Yuan forces only controlled one city within the province, and Yuan Tan's position was only a commandant. He fought Tian Kai to a truce in 193. Yuan Tan was quite successful on his expansion, and was welcomed by the common people of the Province. Although adept in military, Yuan Tan was inept at civil matters – the officials he picked plundered the countryside and accepted bribery, and the taxes collected were below one third of the estimated tax revenue.
Internal conflict within Yuan Shao's forces
In 200, Yuan Tan accompanied his father at the Battle of Guandu against Cao Cao. Yuan Shao, however, was defeated in the conflict and fell sick shortly after returning to his base city of Ye. All along, Yuan Shao had intended to pass on his legacy to his youngest son Yuan Shang, who was favoured by Yuan Shao for his good looks, but the successorship had not been clearly established by the time Yuan Shao died in June 202.
Many officials intended to make Yuan Tan the successor according to seniority of the heirs, but Shen Pei and Pang Ji, two influential advisors, supported Yuan Shang and pushed for the latter to succeed Yuan Shao. When Yuan Tan rushed back from his duty elsewhere, he could not revert the situation, the only thing he could do was to proclaim himself "General of Chariots and Cavalry" (車騎將軍), his father's former title.
In autumn of the same year, Cao Cao launched an offensive against the Yuan brothers. Yuan Tan allied with his brother and stationed his troops in Liyang (northeast of present-day Xun County, Henan) against the attack but his request for more troops was turned down by Yuan Shang, who feared his elder brother would take over military control.