Lian Po
The Qin sent agents into Zhao and Han to spread rumors that Lian Po was too senile and cowardly to fight. King Xiaocheng of Zhao was already dissatisfied with Po's strategy of dragging out the war, so he had Po replaced by Zhao Kuo, son of the late famous Zhao general Zhao She. Upon hearing that the Zhao king fell for the rumor, the Qin secretly replaced Wang He with the renowned general Bai Qi, who was known for being brutally efficient in annihilation battles.