[1] Chang Gun himself passed the imperial examinations late in Emperor Xuanzong's Tianbao era (742-756).
Chang was said to be a capable writer, and both he and his colleague as Zhongshu Sheng, Yang Yan, were respected at the time and often discussed about together.
(Huge armies had greatly assisted Tang in defeating the rebel state of Yan during the Anshi Rebellion).
[5] In 766, he was made the deputy minister of rites (禮部侍郎, Libu Shilang) and continued to be an imperial scholar.
At that time, the eunuch Liu Zhongyi (劉忠翼) and the military governor Ma Lin (馬璘) were both trusted by Emperor Daizong and therefore were powerful.
It was said that Chang paid attention to details and particularly wanted to stamp out any trace of corruption, while Yang had a more thorough view of the entire picture.
For example, as the officials' salaries were low at the time, he proposed an increase — but both he and Han Huang, who was in control of economic matters at the time, decided the scales by their own dislikes, and particularly set low salaries for two officials they disliked, Zhang Can (張參) and Zhao Ji (趙惎).
It was said that while Chang's reforms ended the era of bribery-influenced promotions, it also caused government work to grind to a halt.
[2] In 778, there was an incident when the general Zhu Ci submitted what he thought to be a sign of fortune – a mouse living peacefully with a cat and her kittens.
Chang advocated that because, by custom, Emperor Dezong was to wear mourning clothes for 27 days, so should the officials.
Pursuant to the customs at the time, Chang, in the article of accusation, also signed Guo's and Zhu's names for them.