the central fort would be built in modern Baotou; and the western fort would be built in modern Bayan Nur.) The chancellor Tang Xiujing, himself a successful general, opposed, believing that the forts would be difficult to defend and would eventually fall into Eastern Tujue hands, but after repeated requests by Zhang, Emperor Zhongzong approved. The forts were completed in 60 days, and Zhang further built scout stations north of Mount Niutouchaona (牛頭朝那山, in modern Baotou). Apparently also at his suggestion, the ethnically Tufan general Lun Gongren () was made the forward commander of an army that patrolled the Nuozhen River (諾真水, flowing through modern Baotou). It was said that thereafter, Eastern Tujue forces did not dare to cross the Yin Mountains, and the northern prefectures of the empire no longer needed to worry about Eastern Tujue attacks, allowing defense forces to be decreased in size. The three forts built by Zhang had gates that did not have a secondary gate inside the primary gate, and also did not have defensive bulwarks. When he was asked the reason, he stated: It was only later when another general, Chang Yuankai (), replaced him that the secondary gates were built, and it was said that the people at the time, as a result, respected Zhang and disrespected Chang. It was also said that while he was commanding the forces in Shuofang, he had retained on his staff such officials as Zhang Jingzhong (), He Luan (), Kou Ci (), Wang Yicong (), Liu Tiwei (), Liu Yanzhao (), and Chao Liangzhen (). These officials were capable, and later became important officials in the administration, leading to people praising Zhang Rendan for his ability to select officials. Later in 708, Zhang was given the designation Tong Zhongshu Menxia Sanpin (), making him a chancellor de facto. He was also created the Duke of Han. Under this arrangement, he would return to Chang'an in the spring to serve as chancellor, and in the fall he would again go to Shuofang to defend the border. On an occasion when he departed, Emperor Zhongzong personally wrote a poem to send him off and awarded him with much treasure. During Emperor Shang's reign, Emperor Ruizong's second reign, and Emperor Xuanzong's reign In 710, Emperor Zhongzong died suddenly—a death that traditional historians believed to be poisoning carried out by his powerful wife Empress Wei and daughter Li Guo'er