The rebellion of An Lushan 安祿山 (703-757), in Chinese known as the "rebellion of An [Lushan] and Shi [Siming]" (An Shi zhi luan 安史之亂), was an eight-year long disturbance of the Tang empire 唐 (618-907).
The rebellion was possible because both persons, holding the positions of military commissioners (jiedushi 節度使) had in their jurisdictions practically independent power from the Tang court in military, but also in financial and civil affairs. The office of military commissioner had been created by Emperor Ruizong 唐睿宗 (r. 684, 710-712) for the defence of border regions. It began with a few places that were enlarged to ten during the early reign of Emperor Xuanzong 唐玄宗 (r. 712-755). The same sovereign neglected the metropolitan guards around the capital Chang'an 長安 (today's Xi'an 西安, Shaanxi) and thus critically weakened the defence of the dynasty against the military power of regional commissioners. In 742, the total military strength of the Tang empire was 574,000 troops, of which 490,000 belonged to "border regions" (Yang 1992).
In 742, An Lushan was appointed military commissioner of Pinglu 平盧 (today's Chaoyang 朝陽, Liaoning), and ten years later also controlled the commissions of Fanyang 范陽 (Beijing) and Hedong 河東 (Taiyuan 太原, Shanxi) which means that he had total control over northeast China. An Lushan was well aware that the military defence of Chang'an was rather weak, and his intimate relationship with Emperor Xuanzong and his consort Yang Guifei 楊貴妃 (719-756) offered him insight into the inefficiency of the court bureaucracy. Moreover, he was at odds with Counsellor-in-chief, Yang Guozhong 楊國忠 (700-756), a cousin of Yang Guifei.
This enmity was the main impetus for him to declare a rebellion in December 755, announcing that he would punish Yang Guozhong for his misdeeds. He marched from Fanyang and quickly proceeded through the northeast, where governors and magistrates fled, surrendered or were captured. The rebel quickly advanced to the secondary capital Luoyang 洛陽 (today in Henan), where the court had sent an army to, with 60,000 untrained men under the command of Feng Changqing 封常清 (d. 756). The imperial army was defeated, and Feng, along with General Gao Xianzhi 高仙芝 (d. 756), retreated to the Tongguan Pass 潼關. Believing the slanders of court eunuchs, Emperor Xuanzong had the two generals executed for treason, and ordered the old and ailing general Geshu Han 哥舒翰 (699-757) to hold the Pass. In early 756, An Lushan adopted the title of Emperor of Yan 燕, and handed over his former territories to Shi Siming 史思明 (703-761), who was appointed regulatory commissioner (jinglüeshi 經略使)of Hebei 河北.
In the meantime, popular resistance against the rebels was formed by Yan Zhenqing 顏真卿 (709-784), governor (taishou 太守) of Pingyuan 平原, and Yan Gaoqing 顏杲卿 (692-756), governor of Changshan 常山. They were supported by imperial contingents from the Shuofang region 朔方 (approx. modern Ningxia) under the command of Guo Ziyi 郭子儀 (697 or 698-781) and Li Guangbi 李光弼 (708-764). This combination was very successful and pushed back the rebel troops and even threatened their supply in the hinterland of Luoyang. An Lushan at that time even considered withdrawal to the northeast.
Yet the rivalry between Yang Guozhong and Geshu Han spoiled the success of Guo and Li. Yang suggested to the Emperor that Geshu Han might go over to attack which the sovereign accepted. Yet the advance failed utterly, and Geshu Han was not just pushed back to the Tongguan Pass, but even lost this position, leaving Chang'an open to the enemy. Emperor Xuanzong thereupon decided to evacuate the court and transfer it to Chengdu 成都 (today in Sichuan) which means that the whole court had to cross to Qingling Range 秦嶺. The dramatic culmination of the Emperor's flight was the mutiny at Mayi Station 馬嵬驛 (Xiping 興平, Shaanxi), where the imperial troops killed Yang Guozhong and forced Yang Guifei to hang herself. The devastated emperor travelled on to Chengdu, but the Heir Apparent, prince Li Heng 李亨, refused to accompany his father and instead went to Lingwu 靈武 (Ningxia), where he declared his emperorship in August 756 (later known as Emperor Suzong 唐肅宗, r. 756-762).
In the meantime, An Lushan sent Sun Xiaozhe 孫孝哲 (d. 759) to occupy Chang'an, while he remained in Luoyang. In Chang'an, former enemies of An Lushan were massacred, while those who accepted An Lushan's regime, were guided to Luoyang to serve the usurper. Yet the control of Chang'an by the rebels ran out of the rudder, and the occupants became an easy pray for popular resistance and the advancing relief army of the Tang.
Somewhat to the south, in Nanyang 南陽 (Dengxian 鄧縣, Henan), Lu Jiong 魯炅 (703-759) resisted the siege of An Lushan's troops for a year, before he withdrew to Xiangyang 襄陽 (today in Hubei), from where he blocked the rebels from advancing into the middle Yangtze region and the Han River 漢水 valley. Zhang Xun 張巡, district magistrate of Zhenyuan 真源 (Luyi 鹿邑, Henan), assembled a militia army of several thousand troops that successfully defended the city of Yongqiu 雍丘 (Qixian 杞縣, Henan), and then liaised with the army of governor Xu Yuan 許遠 (709-757). Together, the two leaders held Suiyang 睢陽 (Shangqiu 商丘, Henan) for nearly a year. Local military actions like those helped the Tang government to assemble more strength for the liberation of its heart lands.
The surviving troops of Guo Ziyi and Li Guangbi were reorganised and marched to Lingwu, where the generals were received by the new emperor. This contingent of 50,000 was reinforced by the troops of the military commissions that were not occupied yet, namely Hexi 河西 (Wuwei 武威, Gansu), Beiting 北庭 (Pochengzi 破城子 near Jimsar 吉木薩爾, Xinjiang), and Anxi 安西 (Kuche 安西, Xinjiang). The court also won the support of the Uyghurs (Huihe 回紇), Khotan (Yutian 于闐), and other city states of the Tarim Basin.
In February 757, An Lushan was assassinated by his own son, who then became the leader of the rebellion. Yet from that time on, the strength of the rebel armies vanished. Li Guangbi successfully repelled inimical advances to Taiyuan. Guo Ziyi took the region of Hedong 河東 (Yongji 永濟, Shanxi), and thus destroyed the right (or northern) flank of the rebels which made the liberation of the two capitals easier. Chang'an was freed in autumn by a joint corps of the Prince of Guangping 廣平王 Li Chu 李俶 (the eventual Emperor Daizong 唐代宗, r. 762-779), Guo Ziyi, and Uyghur and troops from the Western Region. Just a month later, Luoyang fell to the imperial troops. An Qingxu fled to Yejun 鄴郡 (close to Anyang 安陽, Henan). Shi Siming decided not longer to support the patricide and surrendered his 80,000 troops to the Tang. He was first rewarded with the title of Prince Guiyi 歸義王 "Homecoming Righteousness" and appointed military commissioner of Fanyang, but many advisors at the court feared his disloyalty. Becoming aware of these suspicions, Shi Siming decided to change sides again and joined An Qingxu.
In autumn 758, Guo Ziyi and Li Guangbi commanded a joint army of 200,000 troops, raised in nine military commissions. It stood nominally under the command of the court eunuch Yu Chao'en 魚朝恩 (722-770). The army besieged the city of Yecheng 鄴城 (Yejun) for half a year, before it was scattered into the wind by Shi Siming in spring 759. The failure of this large imperial army was not due to An Qingxu's military superiority, but rather to lacking coordination. The victor of Yecheng killed An Qingxu and marched to Fanyang, where he took the throne of the empire of Yan. In early autumn, Shi Siming occupied Luoyang once more, and the city was only liberated by Li Guangbi's troops in spring 761.
A month later, Shi Siming met the same fate as An Lushan and was killed by his own son Shi Chaoyi 史朝義. Yet the latter was not able to keep the rebel army together. More and more troops surrendered to the Tang. In autumn 762, the region around Luoyang was cleared by Uyghur troops, and Shi Chaoyi fled to Mozhou 莫州 (Renqiu 任丘, Hebei), and then to Fanyang, where he was finally forced by his own generals to commit suicide.
The An Lushan Rebellion is often seen as the turning point in the history of the Tang dynasty. Even if the rebellion was suppressed in the end by a large alliance of the imperial dynasty with various players, including local militia and foreign support, the dynasty did not alter the structure of military commissions generally, but only followed the old principle of making their territories smaller in order to disempower individual commissioners. Thus, in giving out of their hands the suzerainty over finance and military matters, the Tang dynasty had to fall back on certain reforms in the financial sector to sustain the empire which helped them to survive for another 150 years. One political consequence was the loss of the Western Territories which fell for decades to come to the kingdom of Tibet.