Just when everyone thought this battle would be a solo performance of the 7th Corps of the Great Tang, the coordination of the Tang Army began to show its power.
The 6th Corps of Tang from Chu Territory took advantage of the fact that Zhang Xuan's main troops moved south, launching a fierce attack on the Xishan Fortress. In just two days, they annihilated the defending forces and seized this important strategic stronghold.
Subsequently, the Tang Army entered Shu Territory from the Xishan Fortress, charging from the highlands into the plains of Shu Territory.
This caused the Qin Army's defense line to collapse entirely, exposing the flank of Zhang Xuan's main forces, who were fiercely attacking the 7th Corps, to the onslaught of the 6th Corps.
Despite Zhang Xuan's utmost efforts to restore his flanking defense line, he ultimately failed: the Qin Army collapsed across the line, in a more dismal defeat than in Chu Territory.
