After Han's departure, Duan had his associate Qi Lingyue () forge an order from Yao ordering Han to return to Chang'an, thus aborting the attack. Meanwhile, Zhu had convened a meeting with Li Zhongchen, Yuan, Yao, and Duan, to discuss plans for him to take the throne. At the meeting, Duan tried to assassinate Zhu, but failed. Duan was killed by Zhu's guards despite Zhu's attempt to spare him. On November 6, Zhu declared himself the emperor of a new state of Qin. He made Yao, Li Zhongchen, and Yuan his chancellors, and Zhu Tao crown prince. Zhu Ci made it a priority to capture Fengtian to extinguish the hopes of Emperor Dezong's being restored. He left Li Zhongchen and Qiu Jingzhong () in charge of Chang'an, and personally led his army, assisted by Yao Lingyan and Zhang Guangsheng, to Fengtian. He put Fengtian under siege, and despite the efforts of the Tang generals Hang Yougui () and Hun Jian in fighting off the Qin siege, Fengtian was soon in a desperate state, with its food supplies cut off. Tang resistance forces were then harassing the Qin forces left at Chang'an, and in response, Zhu intensified his siege of Fengtian. However, after Fengtian was under siege for more than a month, Li Huaiguang, who had been fighting Wang Wujun and Tian Yue to the east but immediately headed toward Chang'an upon hearing of Emperor Dezong's plight, arrived with his elite Shuofang Army. On December 18, with Li Huaiguang not quite yet at Fengtian but having defeated Qin forces at Liquan (醴泉, in modern Xianyang), Zhu, fearful that he would be defeated by Li Huaiguang, lifted Fengtian's siege and returned to Chang'an. He would not threaten Fengtian again, although he tried to keep the morale of his forces in check at Chang'an by periodically spreading rumors that Fengtian had fallen. By this point, however, it was said that he controlled little more than Chang'an itself. It was the consensus at the time that if Li Huaiguang had arrived three days later than he actually did, Fengtian would have fallen. On January 27, 784, apparently trying to change his fortune, Zhu changed the name of his state to Han.