Zhang Fei in the context of "Guandi"

The Campaign against Dong Zhuo was a punitive expedition initiated by a coalition of regional officials and warlords against the warlord Dong Zhuo in 190 in the late Eastern Han dynasty. The members of the coalition claimed that Dong had the intention of usurping the throne by holding Emperor Xian hostage and by establishing a strong influence in the imperial court. They justified their campaign as to remove Dong from power. The campaign led to the evacuation of the capital Luoyang and the shifting of the imperial court to Chang'an. It was a prelude to the end of the Han dynasty and, subsequently, the Three Kingdoms period.

In the 14th-century historical novel Romance of the Three Kingdoms, the campaign is memorable for at least two famous incidents: one is Guan Yu's slaying of Hua Xiong; the other is the three-on-one duel between the three sworn brothers (Liu Bei, Guan Yu, Zhang Fei) and Lü Bu. The two scenes are often reenacted in Chinese opera along with other famous scenes from the novel. Both incidents however, are fictional; Hua Xiong was captured and executed by Sun Jian after a brief battle. Liu, Guan and Zhang did participate in the campaign although their actions are not further described, with no mention that they dueled with Lü Bu, who, historically, was defeated by Sun Jian in battle.

Guan Yu ([kwán ỳ] ; d. January or February 220), courtesy name Yunchang, was a Chinese military general serving under the warlord Liu Bei during the late Eastern Han dynasty of China. Along with Zhang Fei, he shared a brotherly relationship with Liu Bei and accompanied him on most of his early exploits. Guan Yu played a significant role in the events leading up to the end of the Han dynasty and the establishment of Liu Bei's state of Shu Han during the Three Kingdoms period. While he is remembered for his loyalty towards Liu Bei, he is also known for repaying Cao Cao's kindness by slaying Yan Liang, a general under Cao Cao's rival Yuan Shao, at the Battle of Boma. After Liu Bei gained control of Yi Province in 214, Guan Yu remained in Jing Province to govern and defend the area for about seven years. In 219, while he was away fighting Cao Cao's forces at the Battle of Fancheng, Liu Bei's ally Sun Quan broke the Sun–Liu alliance and sent his general Lü Meng to conquer Liu Bei's territories in Jing Province. By the time Guan Yu learned about the loss of Jing Province after his defeat at Fancheng, it was too late. He was subsequently captured in an ambush by Sun Quan's forces and executed at Linju, Xiangyang Commandery (臨沮, present-day Nanzhang County, Xiangyang City, Hubei).

Guan Yu's life was lionised and his achievements were glorified to such an extent after his death that he was deified during the Sui dynasty. Through generations of storytelling—culminating in the 14th-century historical novel Romance of the Three Kingdoms—his deeds and moral qualities were greatly emphasized, making Guan Yu one of East Asia's most celebrated paragons of loyalty and righteousness. He is remembered as a culture hero in Chinese culture and is still worshipped by many people of Chinese descent in China, Taiwan, and other countries today. In religious devotion, he is reverentially called the "Emperor Guan" (Guān Dì) or "Lord Guan" (Guān Gōng). He is a deity worshipped in Chinese folk religion, popular Confucianism, Taoism, and Chinese Buddhism, and small shrines to him are almost ubiquitous in traditional Chinese shops and restaurants.