What does Guan Gong mean by going to Maicheng?

Guan Yu's last resort was to go to Maicheng, and his death was imminent.

Later, people used this sentence to describe people who can succeed in everything, and sometimes they stumble and fail. It is a metaphor for despair. It describes that people who can succeed in everything sometimes fail.

The allusion of Guan Yu's defeat in Maicheng:

In the twenty-fourth year of Jian 'an, Guan Yu attacked Fancheng, and the seven imperial armies flooded and the military strength increased greatly. Cao Cao once proposed to move the capital to avoid its sharpness. In October of the 24th year of Jian 'an (2 19), General Monroe of Jiangdong sneaked into Jingzhou when Guan Yu confronted Commander Coss of Fancheng, and captured Guan Yu's stronghold Jiangling. Guan Yu was attacked on both sides, so he quickly withdrew from Fancheng and returned to the west to station in Maicheng. Lv Meng adopted the strategy of disintegration, which made Guan Yu's soldiers unwilling to fight and gradually dispersed.

Guan Yu was isolated and stuck to Maicheng. Sun Quan sent someone to induce Guan Yu to surrender. Guan Yu pretended to surrender, put up a flag at the head of the city and pretended to be a sergeant, but he escaped, only a dozen riders followed. Sun Quan sent Zhu Ran and Pan Zhang to cut off Guan Yu's various back roads, captured Guan Yu and his son Guan Ping alive in Linzhou and immediately executed them.