During the Shu Han period, Emperor Liu Bei appointed Zhuge Liang as his prime minister. With Zhuge Liang's guidance, the kingdom flourished—its people prosperous and its lands well-governed.
Soon after, Liu Bei died, and his son Liu Shan succeeded the throne. Liu Shan, historically known as "Liu Adou," was incompetent and indulged only in pleasure, so he entrusted all military and political power to Zhuge Liang.
Zhuge Liang, a steadfast advocate of allying with Wu to attack Wei, simultaneously forged ties with the Eastern Wu and launched a southern campaign to pacify Meng Huo, stabilizing the border before building up strength and preparing for a northern expedition.
After some time, Zhuge Liang felt his forces were strong enough and decided to march from Qishan to attack the Kingdom of Wei. Before departing, he submitted a memorial to the young emperor Liu Shan, urging him to heed loyal advice, appoint virtuous ministers, and strengthen the state. This memorial became the famous "First Memorial on the Expedition."
However, this Northern Expedition did not succeed. After his defeat, Zhuge Liang had no choice but to retreat back to Shu.
A few years later, Zhuge Liang decided to launch another northern campaign. Some ministers opposed the move, so he submitted a memorial to the young emperor, analyzing the strategic situation: "Shu Han and Wei are irreconcilable—if we do not strike them, they will strike us." Emperor Liu Shan read it and approved the campaign.
This second memorial is the famous "Later Memorial to the Throne on the Expedition." In its closing, Zhuge Liang declared his unwavering loyalty to the state, vowing to "bend every effort and exhaust every ability, serving until death."
Zhuge Liang's "First Memorial on Dispatching the Army" and "Second Memorial on Dispatching the Army," celebrated for their unwavering loyalty to the state, became renowned prose masterpieces in history and hold significant literary value.
"Jugong jincui" is often used together with "si er hou yi," meaning to be cautious and exert one's utmost effort in service until death.
Source: *Records of the Three Kingdoms*, "Biography of Zhuge Liang"
Meaning of the Idiom: Later, the Chinese idiom "鞠躬尽瘁" came to describe how to be cautious and exert one's utmost effort in service until death.