a Khitan attack, had ordered the people of the prefecture to all move within the prefectural capital's walls, drawing much fear and resentment from the people. When Di arrived, he, judging the Khitan forces to be still far away, ordered that the people be allowed to return to their homes and farms, gaining much gratitude from the people. After Sun's forces collapsed in 697 after a surprise attack by the Eastern Tujue khan Ashina Mochuo against his home base, Wu Zetian had Di, the chancellor Lou Shide, and Wu Yizong (武懿宗) the Prince of Henan (a grandson of her uncle Wu Shiyi (武士逸)) to tour the region north of the Yellow River to try to pacify the people. Later in 697, Di was serving as the commandant at You Prefecture (幽州, roughly modern Beijing), when, at Lou's recommendation, Wu Zetian recalled him to Luoyang to serve as Luantai Shilang (鸞臺侍郎), the deputy head of the examination bureau of government (鸞臺, Luantai), and again gave him the chancellor designation of Tong Fengge Luantai Pingzhangshi. He submitted a petition advocating that descendants of Western Tujue and Goguryeo rulers be found and be given their ancient lands, to help defend against Eastern Tujue and Tufan attacks—a petition that was not accepted but was said to be well regarded by other officials. At that time, Wu Zetian's son Li Dan (the former Emperor Ruizong) was crown prince, but Wu Zetian's nephews Wu Chengsi the Prince of Wei and Wu Sansi the Prince of Liang both had designs on the position, and repeatedly had their associates reason with Wu Zetian that there had never been an emperor who made someone of a different family name his heir. Di, on the other hand, repeatedly argued to her that it is more proper for her to make her son her heir, and that Li Dan's brother Li Zhe the Prince of Luling, himself a former emperor that Wu Zetian removed in 684, be recalled to the capital, a suggestion echoed by fellow chancellors Wang Fangqing and Wang Jishan, and Wu Zetian began to agree. On one occasion, Wu Zetian asked him, "Last night I dreamed of a large parrot that had two broken wings. What do you think it means?" Di responded: It was said that thereafter, Wu Zetian stopped considering Wu Chengsi or Wu Sansi as heir. Meanwhile, another close advisor of Wu Zetian's, Ji Xu,