Volume 22 of the Treatise on Armament Technology Wubei Zhi

Studies of Military Strategy: The Qi Era This refers to the period of the Southern Qi dynasty, during which these Northern Wei events occurred.

Mu Tai, a high official of the Northern Wei, was sent out to serve as the Regional Governor of Dingzhou In modern Hebei province.. He personally submitted a report stating that he had suffered from a long-term illness and that the local soil was excessively damp; he begged to be moved to Hengzhou The region surrounding the old capital, Pingcheng, in modern Shanxi.. The Emperor of Wei accommodated him by moving the Regional Governor of Hengzhou, Lu Rui, to Dingzhou, and appointing Tai to replace him.

When Tai arrived at his new post, Rui had not yet departed. Consequently, the two of them conspired together to stage a rebellion. They attempted to install Yuan Yi, the Prince of Yangping, as their leader. Prince Yi feigned his consent to their plan, but secretly reported the conspiracy to the throne.

At that time, Yuan Cheng, the Prince of Rencheng, was ill. The Emperor summoned him for an audience and told him: "Mu Tai is plotting a revolt. We have only just moved the capital This refers to the historic move from the northern city of Pingcheng to Luoyang in 494 CE, which many northern elites opposed., and the northerners still long for their old homeland. With disturbances now split between the north and the south, my position here in Luoyang is not yet stable. This is a grave matter that only you can handle. You must force yourself to travel north for me. If their faction is still weak, go directly and capture them. If they have already grown powerful and numerous, you are authorized to exercise imperial power chengzhi: the authority to issue orders and mobilize troops in the Emperor's name without waiting for further permission to call up the troops of Bingzhou and Sizhou to strike them."

The Emperor then granted Cheng the imperial tally A symbolic staff of office representing the Emperor's direct authority.. When Cheng reached Yanmen, the local Governor arrived under the cover of night to report that Tai had already led his troops westward to join the Prince of Yangping. Cheng immediately ordered his forces to advance. The Assistant Minister, Meng Bin, cautioned him, saying: "The outcome of this situation is still impossible to measure; we should proceed strictly according to the original imperial decree."