Duan responded, "Looking through the book and memorizing sentences is not a great achievement," and he refused to sit for the examination.
[2] Duan later came to serve under the military governor (Jiedushi) of Anxi Circuit (安西, headquartered in modern Aksu Prefecture, Xinjiang), Fumeng Lingcha (夫蒙靈詧), and after he distinguished himself in a Fumeng-commanded campaign against Humi (護蜜, centered on modern Faizabad, Uttar Pradesh) in 745, he was made a key officer in the Anxi army.
In the aftermath of the defeat, Gao's deputy Li Siye suggested full retreat by Gao—abandoning some of the soldiers who had become lost after the battle.
Duan rebuked Li Siye, stating, "Fleeing in light of your fear of the enemy is no bravery, and sparing yourself to allow others to be trapped is no kindness."
Li Siye was embarrassed, and he and Duan subsequently made an attempt to gather the 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.
Duan Xiushi rebuked Li Siye:[3] How can it be that the emperor requests emergency aid and a subject calmly refuses?
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.
The Anxi army supported Li Siye's subordinate Lifei Yuanli (荔非元禮) to take over the command, and Emperor Suzong agreed.
This continued after Bai was made the military governor of Fufang Circuit (鄜坊, headquartered in modern Yan'an, Shaanxi).
Subsequently, Bai was made the military governor of Binning Circuit (邠寧, headquartered in modern Xianyang, Shaanxi), and Duan continued to serve as his deputy.
At one time, when the circuit lacked food, Bai temporarily moved his army to Fengtian (奉天, also in modern Xianyang).
However, Fengtian was then in a state of confusion as the local government had collapsed, and the soldiers, in response, were pillaging the area.
Duan volunteered to again be discipline officer, and after one month, there was an incident when 17 of Guo Xi's soldiers, in a dispute with a wine seller, killed him and destroyed the winemaking equipment.
Around the new year 769, at the suggestion of the chancellor Yuan Zai, the three prefectures belonging to Binning Circuit were merged into Guo Ziyi's command.
They were displeased about being moved once again, and the officer Wang Tongzhi (王童之) subsequently organized a plot to rise in mutiny.
When he received reports that the officers Shi Tinggan (史廷幹), Cui Zhen (崔珍), and Zhang Jinghua (張景華) were plotting mutiny and planning to rise at Ma's funeral, he defused the situation by sending Shi to Chang'an to serve in the imperial guards and sending Cui and Zhang out of the headquarters to other posts.
These proposals included rebuilding Yuan Prefecture (原州, in modern Guyuan, Ningxia), at that time in no-man's land between Tang and Tufan, to use as a forward advance position; and restoring Lingyang Canal (陵陽渠, flowing through Bayan Nur, Inner Mongolia), to allow the soldiers stationed in the area to farm.
Yang was displeased, and he had Duan removed from his military governor position and recalled to Chang'an to serve in the relatively unimportant post of minister of agriculture (司農卿, Si'nong Qing).
In late 783, Jingyuan soldiers, who had been summoned to Chang'an in anticipation of being sent east to battle warlords Zhu Tao (Zhu Ci's brother), Li Na, Wang Wujun, and Tian Yue, who had declared themselves princes, were at Chang'an, when they were angered by the lack of rewards given by Emperor Dezong.
On November 2, 783,[6] they rose in mutiny and, with the imperial guard soldiers inadequate to resist them, Emperor Dezong fled to Fengtian.
Duan, however, secretly plotted with his subordinates Liu Haibin (劉海賓), He Mingli (何明禮), and Qi Lingyue (岐靈岳), to assassinate Zhu and welcome Emperor Dezong back.
On November 6,[1] Zhu convened a meeting with Li, Yuan, Yao, and Duan, to discuss the matters of declaring himself emperor.