Following the counsel of his chancellor Zhang Lu – formerly Fan Ju of Wei – King Zhaoxiang of Qin launched a campaign against Han and Wei, executing the doctrine of “Ally with the Distant, Attack the Nearby”.
After the collapse of Su Qin’s Vertical Alliance (Hezong), a new threat emerged to Qin’s ambition: the alliance between Qi and Chu, the two most powerful eastern states. United, they could block Qin’s path to unification.