human
What was the reasoning behind Wei Yan's Ziwu Valley Plan?
assistant
Wei Yan's reasoning for his Ziwu Valley Plan was that he received intelligence that the defender of the strategic city Chang'an, Xiahou Mao, was cowardly and incompetent. Thus, he reasoned, it would be easy for him to take 5,000 troops (and another 5,000 to carry supplies) across the Qin Mountains via the Ziwu Valley (子午谷) and into Chang'an.