scattered troops to organize them into an orderly retreat. After the army returned to Anxi, Li Siye recommended Duan to Gao to serve as the circuit's secretary. In 753, when Gao's successor Feng Changqing attacked Greater Bolü (大勃律, centering modern Gilgit, Pakistan), after the initial successes, Feng was set to pursue the Greater Bolü king, when Duan pointed out that the king's flight might be a trap—and at Duan's suggestion, Feng made a thorough search in the area of the battle, finding many Greater Bolü soldiers who had hidden themselves, ready for a surprise attack. This allowed Feng to finish the victory over Greater Bolü. Duan was thereafter promoted in rank. During Emperor Suzong's reign In 755, the general An Lushan rebelled at Fanyang (范陽, in modern Beijing) and established a new state of Yan. In 756, his forces approached the Tang capital Chang'an, forcing Emperor Xuanzong to flee to Chengdu. Emperor Xuanzong's son and crown prince Li Heng did not follow him to Chengdu, but instead fled to Lingwu, where he was declared emperor (as Emperor Suzong), an act that Emperor Xuanzong later recognized. Emperor Suzong ordered that the key military circuits send armies to aid him. When his order reached Anxi, the military governor Liang Zai (), after consulting with Li Siye, initially decided not to act on the order and to wait for further development. Duan Xiushi rebuked Li Siye: Li Siye was embarrassed, and he subsequently met with Liang and persuaded Liang to commission an army, with Li Siye himself in command and Duan as deputy, to join Emperor Suzong at Lingwu. Soon thereafter, Duan's father died, and he spent time in morning. As Li Siye felt that Duan's service was indispensable, he requested that Duan be recalled into active service. In 757, a joint Tang-Huige army recaptured Chang'an and then the eastern capital Luoyang, forcing An Lushan's son and successor An Qingxu to flee to Yecheng. Tang forces put Yecheng under siege, and Li Siye, one of the Tang commanders at the siege, made Duan the prefect of Huai Prefecture (懷州, in modern Jiaozuo, Henan) to be responsible for logistics—the shipping of food supplies from the area to the army at Yecheng. In spring 759, Li Siye died in battle during the siege. The Anxi army supported Li Siye's subordinate Lifei Yuanli () to take over the command, and Emperor Suzong agreed. Duan remained as