In 662 BCE, Duke Zhuang of Lu died. With the support of his full younger brother, Prince You, Prince Ban ascended the throne. However, Duke Zhuang's half-brother, Prince Qingfu, a greedy and power-hungry man, sought the throne for himself. Within two months of Prince Ban's reign, Qingfu had him assassinated. Prince You, who had backed Ban, fled to the state of Chen.
After Qingfu sent assassins to kill Prince Ban, he installed Duke Min as the new ruler of Lu. His orchestration of internal strife ignited fierce outrage among the people, but Qingfu remained undeterred, continuing to sow chaos in hopes of fishing in troubled waters, plunging the state of Lu into relentless turmoil.
At the time, Duke Huan of Qi, with Guan Zhong's help, had already made Qi quite powerful and had been officially appointed as the chief of the feudal lords by King Hui of Zhou, legitimately becoming the overlord of the Central Plains. Naturally concerned about the internal turmoil in the state of Lu, he sent his minister Zhong Sunqiu to investigate the situation there. Soon after, Zhong Sunqiu reported his findings to Duke Huan and concluded, "If Qing Fu is not removed, the disasters in Lu will never end!"
And indeed it happened. A year later, Qingfu murdered another ruler, Duke Min of Lu. Within just two years, two dukes of Lu had been killed, plunging the state into chaos. The people seethed with hatred for Qingfu. Realizing he could no longer remain in Lu, Qingfu fled to the state of Ju.
After Duke Xi of Lu ascended the throne, he recognized that Qing Fu's continued existence posed a grave threat to the state and requested that the Ju state send Qing Fu back to Lu. Aware of his heinous crimes and knowing he would face a grim fate upon his return, Qing Fu took his own life along the way.
Later, the idiom "Until Qingfu is dead, the troubles of Lu will not end" came to be used to describe how a nation cannot find peace until the chief instigator of internal strife is eliminated.
Source: *Zuo Zhuan*, "First Year of Duke Min"
Meaning of the Idiom: Later, the Chinese idiom "庆父不死，鲁难未已" came to describe how a nation cannot find peace until the chief instigator of internal strife is eliminated.