[1]), courtesy name Jingci (敬辭), formally the Duke of Fufeng (扶風公), was a general of the Chinese Tang dynasty, most well known for his failures against Dali incursions but successes against the rebel Pang Xun (with the assistance of the Shatuo chieftain Zhuye Chixin).
[1] His grandfather was the general Kang Rizhi (康日知), who served under Emperor Dezong and carried the title of Prince of Kuaiji.
It was said that the army at Tiande lacked horses at that time and therefore was repeatedly suffering defeats when non-Han Chinese incursions occurred.
Kang reduced the budgets in areas that he felt were unnecessary in order to bolster the number of horses the base could afford, and it was said that after he did so, the Tiande army had more successes.
The military governor of Lingnan West Circuit, Zheng Yu (鄭愚), who was a career civilian, was fearful of Dali forces and submitted a petition requesting to be replaced by a general.
In the aftermaths, Kang was gripped by fear, and the defenses for Yong Prefecture were actually built by his deputy Li Xingsu (李行素).
Subsequently, the military governor of neighboring Lingnan East Circuit (嶺南東道, headquartered in modern Guangzhou, Guangdong), found out what happened, and reported this to the chancellors.
[4] Yao's death shocked and dismayed Pang, who, under the suggestion of his strategist Zhou Chong (周重), tried to show resolve by officially declaring independence from the imperial government and killing Cui and his top staff members, as well as cutting off the limbs of the Huainan Circuit (淮南, headquartered in modern Yangzhou, Jiangsu) officer Li Xiang (李湘) and the eunuch monitor Guo Houben (郭厚本) and delivering them to Kang's army to try to strike terror into Kang's soldiers.
Pang subsequently launched a surprise attack on the Weibo Circuit (魏博, headquartered in modern Handan, Hebei), stationed to Xu Prefecture's north, and then turned west, ready to engage Kang.
Zhang Xuanren then suggested to Kang that he pretend to be still leading a rebel army and use trickery — pretending that Su Prefecture had fallen and that he was fleeing — to capture the nearby rebel base of Fuli (苻離) as well, and Zhang Xuanren's strategy succeeded, allowing the imperial forces to capture Fuli.
[4] To reward Kang Chengxun for his contributions, Emperor Yizong commissioned him as the military governor of Hedong Circuit (河東, headquartered in modern Taiyuan, Shanxi) and gave him the honorary chancellor title of Tong Zhongshu Menxia Pingzhangshi (同中書門下平章事).
[4] However, in 870, the chancellors Lu Yan and Wei Baoheng (Emperor Yizong's son-in-law) submitted accusations that Kang was too tentative against Pang Xun, failed to wipe out all of the rebels, and was too anxious to seize the spoils of war.
As a result, Kang was demoted to be the teacher of Emperor Yizong's son Li Ji (李佶) the Prince of Shu, but with his office at Luoyang.