During the Three Kingdoms period, after the death of Shu's ruler Liu Bei, the prefect of Jianning, Yong Kai, grew arrogant and plotted rebellion. Seeking a powerful ally, he sent a letter to Sun Quan and pledged allegiance to Wu. Sun Quan appointed him prefect of Yongchang and ordered him to take office immediately.
At that time, the former governor of Yongchang Commandery had already left office, and the new governor had not yet been appointed. However, the merit officer Lü Kai and the assistant Wang Kang remained loyal to Shu Han. When Lü Kai and Wang Kang received news that Yong Kai had surrendered to the state of Wu, they were filled with indignation.
After receiving his appointment from Eastern Wu, Yong Kai issued several proclamations demanding that Lu Kai and Wang Kang surrender, threatening to attack Yongchang if they refused. Unmoved by the threats, Lu Kai and Wang Kang led the Yongchang garrison to seal the city gates and prepare for battle, vowing to fight Yong Kai to the end.
Meanwhile, Lu Kai sent a reply to Yong Kai. In the letter, Lu Kai angrily condemned Yong Kai's treasonous actions. He cited numerous examples from ancient and modern times to illustrate that upright, patriotic, and hardworking individuals would forever be praised by the people. He urged Yong Kai to change his ways, warning that otherwise, he would face dire consequences.
However, Yong Kai refused to heed Lu Kai's counsel and launched an attack on Yongchang. Upon hearing of the rebellion, Zhuge Liang immediately dispatched troops to suppress it. Before the main army could reach Yongchang, Yong Kai was killed by his own subordinate, Gao Ding, and the rebellion was swiftly quelled.
Upon arriving in Yongchang, Zhuge Liang praised Lu Kai and Wang Kang generously, then petitioned the Later Ruler to appoint Lu Kai as the Prefect of Yunnan and Wang Kang as the Prefect of Yongchang.
Later, the idiom "a sudden change of plans" came to describe quickly turning around and making new arrangements.
Source: *Records of the Three Kingdoms*, "Biography of Lü Kai"
Meaning of the Idiom: Later, the Chinese idiom "翻然改图" came to describe how quickly turning around and making new arrangements.