When Li Yuan was hesitating whether to re-establish the crown prince, there was an even more shocking news, the eighteenth division of the grassland suddenly attacked. Li Yuan had no choice but to release Li Jiancheng from prison and led everyone to hurry back to Chang'an.
Li Jiancheng asked his father to let him lead troops to conquer the eighteen departments of the grassland or defend Chang'an. But Li Yuan didn't trust him and ordered someone to recall Li Shimin urgently.
Li Jiancheng and Pei Lin took advantage of Li Yuan's uneasiness to propose to him to move the capital. They knew that Li Shimin's main forces were concentrated in Chang'an, and once the capital was moved, Li Shimin's power would be greatly weakened. Li Yuan was in a state of confusion at this time, and without thinking too much, he quickly agreed to their proposal to move the capital.
Although Wei Zheng had been working for the crown prince Li Jiancheng, he did not agree with the prince's idea of moving the capital. The two had a disagreement and parted unhappily.
Just when Pei Lin and Li Jiancheng began to plan the agenda of moving the capital and making a lot of money from Zhongda, Li Shimin rushed back to Chang'an in time. As soon as he saw Li Yuan, he immediately stated three reasons for his opposition to moving the capital. His words were sincere and powerful, and they quickly changed Li Yuan's opinion. Li Yuan immediately announced that he would no longer discuss the matter of moving the capital.