During his 34-year reign, he was unable to exercise power alone and was under the control of several of his great ministers and his wife, Empress Wu. The order of the regents were: •
Zhangsun Wuji and
Yu Zhining (649-659) •
Han Yuan,
Lai Ji and
Liu Shi (649-658) •
Li Ji and
Chu Suiliang (649-658) •
Empress Wu (660-683)
Early reign: Political struggles Yonghui era (650–656) Emperor Gaozong's first move as emperor was to cancel a second campaign against Goguryeo that Emperor Taizong had planned for later 649. While Li Tai was disallowed from attending Emperor Taizong's funeral, Emperor Gaozong permitted him to again have a staff and be allowed to use wagons, clothes, and foods of high quality. Emperor Gaozong created his wife Crown Princess Wang empress and made her father Wang Renyou () the Duke of Wei. It was said that early in Emperor Gaozong's reign, he greatly respected both his uncle Zhangsun Wuji and Chu Suiliang and followed their advice, and that therefore, during this part of his reign, the government was organized well and the people were comforted, much like during the reign of Emperor Taizong, although in winter 650, Chu was accused of forcibly purchasing private land and paying below-market price, and was demoted to be a prefectural prefect. (Chu eventually returned to power in 653.) Also in 650, the general Gao Kan () – whose army had been launched by Emperor Taizong against the newly reconstituted Göktürk state under
Chebi Khan Ashina Hubo prior to Emperor Taizong's death—captured Ashina Hubo and brought him back to Chang'an. Emperor Gaozong spared Ashina Hubo and made him a general, putting his people directly under Tang rule. Meanwhile, with two of the states of the
Western Regions previously conquered by Tang and governed by Tang-installed kings,
Kucha and
Karasahr in disturbance, Emperor Taizong returned their previously captured kings, Bai Helibushibi () and Long Tuqizhi () respectively, to their thrones. In 651, the Western Turkic Khaganate prince
Ashina Helu, who had sought and received protection from Emperor Taizong, broke away from Tang and defeated the Western Turkic Khaganate's
Yipishekui Khan, taking over the Western Turkic Khaganate himself and no longer subordinate under Tang. In fall 651, Ashina Helu attacked Tang's Ting Prefecture (, roughly
Changji Hui Autonomous Prefecture, Xinjiang), and Emperor Gaozong responded by commissioning the generals Liang Jianfang () and Qibi Heli () to attack Ashina Helu. Liang and Qibi achieved some victories against Ashina Helu's general Zhuxie Guzhu (), but then withdrew without engaging Ashina Helu. Meanwhile, as Empress Wang was sonless, her uncle, the chancellor
Liu Shi, suggested to her that she ask Emperor Gaozong to create his oldest son Li Zhong, whose mother Consort Liu was of low birth and therefore considered nonthreatening, crown prince so that Li Zhong would be grateful of her in the future. Liu also persuaded Zhangsun to suggest the idea as well, and in fall 652, Emperor Gaozong created Li Zhong crown prince. By this point, however, Empress Wang was facing a major threat from another romantic rival. When Emperor Gaozong was crown prince, he had an affair with one of Emperor Taizong's concubines,
Consort Wu. After Emperor Taizong's death, all of his concubines who did not bear sons, which included Wu, were housed at Ganye Temple () to be
Buddhist nuns. In either 650 or 651, Emperor Gaozong was visiting Ganye Temple to offer incense to Buddha when he saw Consort Wu. Both of them wept. When Empress Wang heard this, she, wanting to divert Emperor Gaozong's favor from Consort Xiao, secretly instructed Consort Wu to grow her hair back, while suggesting to Emperor Gaozong that he take her as a concubine. Consort Wu was intelligent and full of machinations, and therefore, when she first returned to the palace, she acted humbly and flattered Empress Wang, who trusted her greatly and recommended her to Emperor Gaozong. Soon, Emperor Gaozong became enamored with Consort Wu. Meanwhile, Emperor Gaozong's sister
Princess Gaoyang and her husband Fang Yi'ai (, Fang Xuanling's son), were implicated in 652 of conspiring with another brother-in-law Chai Lingwu (), the general Xue Wanche () and Emperor Gaozong's uncle Li Yuanjing () the Prince of Jing to make Li Yuanjing emperor. Fang, knowing that Zhangsun had long been apprehensive of Li Ke, falsely implicated Li Ke in the plot as well, hoping to ingratiate Zhangsun sufficiently that he would be spared. nevertheless, in spring 653, at the suggestion of Zhangsun and
Cui Dunli – despite Emperor Gaozong's initial inclination to spare Li Yuanjing and Li Ke—Emperor Gaozong ordered that Fang, Xue, and Chai be executed, and that Li Yuanjing, Li Ke, and the Princesses Gaoyang and Baling (Chai's wife) be forced to commit suicide. Zhangsun took this opportunity to accuse several other officials friendly with Fang or hostile to him—the chancellor
Yuwen Jie,
Li Daozong the Prince of Jiangxia, and the general
Zhishi Sili () – of being friendly with Fang and had them exiled. He also deposed and exiled Li Ke's mother Consort Yang and Consort Yang's other son Li Yin () the Prince of Shu, as well as Fang's brother Fang Yizhi () and Xue's brother Xue Wanbei (). By 654, both Empress Wang and Consort Xiao had lost favor with Emperor Gaozong, and the former romantic rivals joined forces against Consort Wu, but to no avail, and as a sign of his love to Consort Wu, in 654 he conferred posthumous honors on her father
Wu Shihuo (). Later that year, Consort Wu gave birth to a daughter that died shortly after birth. Evidence implicated Empress Wang as the killer, although some historians believe Consort Wu killed her own daughter in order to frame Empress Wang, but no concrete evidence of this exists. In anger, Emperor Gaozong considered deposing Empress Wang and replacing her with Consort Wu, but wanted to make sure that the chancellors would support this, and so visited Zhangsun's house with Consort Wu, awarding him with much treasure, but when he brought up the topic that Empress Wang was sonless (as an excuse for deposing her), Zhangsun repeatedly found ways to divert the conversation, and subsequent visits by Consort Wu's mother Lady Yang and the official
Xu Jingzong, who was allied with Consort Wu, to seek support from Zhangsun were also to no avail. In summer 655, Consort Wu accused Empress Wang and her mother Lady Liu of using witchcraft. In response, Emperor Gaozong barred Lady Liu from the palace and demoted Liu Shi. Meanwhile, a faction of officials began to form around Consort Wu, including
Li Yifu, Xu, Cui Yixuan (), and Yuan Gongyu (). On an occasion in fall 655, Emperor Gaozong summoned the chancellors Zhangsun, Li Shiji (who by now was using the name Li Ji to observe
naming taboo for Emperor Taizong's name Li Shimin),
Yu Zhining, and Chu to the palace—which Chu deduced to be regarding the matter of changing the empress. Li Ji claimed an illness and refused to attend. At the meeting, Chu vehemently opposed deposing Empress Wang, while Zhangsun and Yu showed their disapproval by silence. Meanwhile, other chancellors
Han Yuan and
Lai Ji also opposed the move, but when Emperor Gaozong asked Li Ji again, Li Ji's response was, "This is your family matter, Your Imperial Majesty. Why ask anyone else?" Emperor Gaozong therefore became resolved. He demoted Chu to be a commandant at
Tan Prefecture (roughly modern
Changsha, Hunan), and then deposed both Empress Wang and Consort Xiao, putting them under arrest and creating Consort Wu, as empress (, huánghòu) and the most powerful woman in the empire (, Tiānxià Mǔ) instead to replace Empress Wang. (Later that year, Empress Wang and Consort Xiao were killed on orders by the new Empress Wu after Emperor Gaozong showed signs of considering their release.) Then, at Xu's suggestion, in spring 656, Emperor Gaozong demoted Li Zhong to be the Prince of Liang and created Empress Wu's oldest son
Li Hong the Prince of Dai crown prince instead. In 655 as well, Emperor Gaozong commissioned the general
Cheng Zhijie () to attack Ashina Helu, but while the campaign saw some victories over Western Turkic Khaganate's substituent tribes Geluolu () and Chuyue (), it was hindered by Cheng's inability to restrain his assistant Wang Wendu () from pillaging and inappropriately halting the army. After the campaign ended in early 657, both Cheng and Wang were deposed from their offices.
Xianqing era (656–661) In 657, Emperor Gaozong commissioned the general
Su Dingfang, who had served under Cheng Zhijie in the earlier failed campaign, to
command a campaign against Ashina Helu, assisted by
Ren Yaxiang and Xiao Siye (). They were joined by the Western Turkic Khaganate's leaders
Ashina Mishe and
Ashina Buzhen, who had submitted to Tang during Emperor Taizong's reign. The campaign caught Ashina Helu by surprise, and Su defeated him in several battles, causing him to flee to the kingdom Shi (, centering modern
Tashkent,
Uzbekistan), which arrested him and delivered him to Su, thus largely ending the Western Turkic Khaganate as an organized state. (Emperor Gaozong would try to continue the Western Turkic Khaganate's existence as a vassal stage by dividing it in half and creating Ashina Mishe and Ashina Buzhen as khans of the two halves.) Meanwhile, Xu Jingzong and Li Yifu, aligned with Empress Wu, and became strong enough to fight for power, began to carry out a campaign of reprisal on her behalf. Empress Wu, on the other hand, persuaded Emperor Gaozong to work with the removal of the chancellors appointed by Emperor Taizong to consolidate the emperor's power. In 657, they accused Han Yuan and Lai Ji of plotting treason with Chu Suiliang, who was then serving as the commandant at Gui Prefecture (桂州, roughly modern
Guilin, Guangxi). Emperor Gaozong demoted Han and Lai to be prefects of distant prefectures, and demoted Chu and Liu Shi to even more distant prefectures—in Chu's case, to the extremely distant Ai Prefecture (愛州, roughly modern
Thanh Hóa Province,
Vietnam), and Chu's subsequent petition, sent from Ai Prefecture, pleading with Emperor Gaozong, fell on deaf ears. Empress Wu's reprisals did not end there. In 659, Zhangsun Wuji became the next target. At that time, two low level officials, Wei Jifang () and Li Chao () had been accused of improper associations, and when Emperor Gaozong put Xu and
Xin Maojiang of investigating, Xu falsely accused Wei and Li to be part of a treasonous plot by Zhangsun. Emperor Gaozong, without meeting with Zhangsun, believed Xu, and put Zhangsun under house arrest in exile at Qian Prefecture (黔州, roughly modern southeastern
Chongqing). Xu further implicated Chu, Liu, Han, and Yu Zhining in the plot as well. Yu was removed from his post. Chu, who had died in 658, was posthumously stripped of all titles, and his sons Chu Yanfu () and Chu Yanchong () were executed. Orders were also issued to execute Liu and Han, although Han died before the execution order reached his location. Meanwhile, Zhangsun, once he reached his place of exile, was forced to commit suicide. It was said that after Han's and Lai's deaths, no official dared to criticize the emperor any further. Also in 659, a vassal of Western Turkic Khaganate (Pin.
Tujue), Duman (), the commander of the
Esegels (aka
Izgil, , Ch.
Asijie,
Sijie ) Tribe, rebelled against Tang
occupation, along with the Western Turkic Khaganate's subject kingdoms
Shule (),
Zhujupo (), and
Yebantuo () (all in modern
Kashgar, Xinjiang). The joint forces commanded by Duman quickly defeated the Tang vassal Yutian (, in modern
Hotan, Xinjiang). In winter 659, Emperor Gaozong sent Su Dingfang against Duman, and once he arrived in the vicinity of Duman's army, he selected 10,000 infantry soldiers and 3,000 cavalry soldiers and made a surprise attack on Duman. When he arrived at Duman's headquarters, Duman was surprised, and after Su initially defeated Duman, Duman was forced to withdraw within the city. Su put the city under siege, and Duman surrendered. In spring 660, Su took Duman back to the eastern capital
Luoyang, where Emperor Gaozong was at the time, to present Duman to him. Some officials requested that Duman be executed, but Su made a plea on Duman's behalf—that he had promised Duman life before Duman surrendered—and Emperor Gaozong stated that while under the law, Duman should die, he would honor Su's promise, and so he spared Duman. On the other end of the Tang atmosphere of influence, on the
Korean Peninsula,
Baekje had been attacking the Tang ally
Silla. Once Su returned from the
Esegel campaign, Emperor Gaozong commissioned him to head over the sea to attack Baekje, in conjunction with Silla. Su quickly captured the Baekje capital
Sabi, forcing Baekje's
King Uija and his crown prince
Buyeo Yung to surrender. Emperor Gaozong ordered that Baekje be annexed as Tang territory. Emperor Gaozong then followed up by commissioning Su, along with Qibi Heli, Liu Boying (), and Cheng Mingzhen (), to attack Goguryeo. In 660, Emperor Gaozong and Empress Wu toured Bian Prefecture (modern-day Taiyuan), and Empress Wu had the opportunity to invite her old neighbors and relatives to a feast. Later that year, Emperor Gaozong began to suffer from an illness that carried the symptoms of painful headaches, persistent dizziness, occasional seizures and loss of vision, generally thought to be hypertension-related or stroke, and Emperor Gaozong began to have Empress Wu make rulings on petitions and suggestions made by officials. It was said that Empress Wu had quick reactions and understood both literature and history, and therefore, she was making correct and error-free rulings. Emperor Gaozong's illness worsened over time, and lasted until his death. If he was well, he also would accept Empress Wu's help, asking her to read the documents to him, he consulted with her on important matters and write down the rulings he had issued. Even until midnight, when he was exploring the memorials, he had Empress Wu by his side to decide if anything went wrong, and he became very dependent on her advice over time, and, as usual, because of his illness, he allowed Empress Wu to act in his name. Thereafter, her authority rivaled Emperor Gaozong's, after this point on, Empress Wu became the undisputed power behind the throne until the death of Emperor Gaozong.), he and she initiated the sacrifices to heaven, which were not completed until the next day. On 12 February, sacrifices were made to earth. He and she gave general promotions to the imperial officials, and it was said that starting from this time, promotions of imperial officials, which were strict and slow during the reigns of Emperors Gaozu and Taizong, began to become more relaxed and often excessive. He and Empress Wu also declared a general pardon, except for long-term exiles.
Japan, India, the
Persian court in exile,
Goguryeo,
Baekje,
Silla, the
Turks,
Khotan, the
Khmer, and the
Umayyad Caliphate all had representatives attending the Feng and Shan sacrifices held by Emperor Gaozong and Empress Wu in 666 at Mount Tai.
Qianfeng and Zhongzhang eras (666–670) In summer 666,
Yŏn Kaesomun died and was initially succeeded as
Dae Mangniji by his oldest son
Yŏn Namsaeng. As Yŏn Namsaeng subsequently carried out a tour of Goguryeo territory, however, rumors began to spread both that Yŏn Namsaeng was going to kill his younger brothers
Yŏn Namgŏn and
Yŏn Namsan, whom he had left in charge at Pyongyang, and that Yŏn Namgŏn and Yŏn Namsan were planning to rebel against Yŏn Namsaeng. When Yŏn Namsaeng subsequently sent officials close to him back to Pyongyang to try to spy on the situation, Yŏn Namgŏn arrested them and declared himself
Dae Mangniji, attacking his brother. Yŏn Namsaeng sent his son (later known as Ch'ŏn Heonseong/Quan Xiancheng (), as Yŏn Namsaeng changed his family name from Yŏn () to observe
naming taboo for Emperor Gaozu, whose personal name was the same character) to Tang to seek aid. Emperor Gaozong and Empress Wu saw this as the opportunity to destroy Goguryeo, and he initially commissioned Qibi Heli to aid Yŏn Namsaeng, and also sent the generals Pang Tongshan () and Gao Kan () to attack Goguryeo. Meanwhile, Empress Wu's sister, the
Lady of Han (who had married the low-level official Helan Yueshi ()), and her daughter
Lady Helan had both been frequently visiting the palace and were said to be "favored" by Emperor Gaozong. When Lady of Han died in 666, Emperor Gaozong created Lady Helan the Lady of Wei, and wanted to let her live in the palace, but hesitated because he thought Empress Wu would be jealous. When Empress Wu heard this, she was indeed jealous, and therefore she poisoned meat offered by her nephews Wu Weiliang () and Wu Huaiyun (), who had been on poor relations with her and whose grandmother were not her mother Lady Yang; she then gave the poisonous meat to Lady Helan, who ate it and died. Empress Wu then implicated Wu Weiliang and Wu Huaiyun in Lady Helan's death and executed them. Around the new year 667, Emperor Gaozong and Empress Wu further commissioned Li Ji to be the overall commander of the attack on Goguryeo, assisted by
Hao Chujun. In fall 667, Li Ji crossed the
Liao River and captured Sinseong (, in modern
Fushun, Liaoning). The Tang forces thereafter fought off counterattacks by Yŏn Namgŏn and joined forces with Yŏn Namsaeng, although they were initially unable to cross the
Yalu River. In spring 668, Li Ji turned his attention to Goguryeo's northern cities, capturing the important city Buyeo (, in modern
Siping, Jilin). In fall 668, he crossed the Yalu and put Pyongyang under siege. Yŏn Namsan and
King Bojang surrendered, and while Yŏn Namgŏn continued to resist in the inner city, his general, the Buddhist monk Shin Seong () turned against him and surrendered the inner city to Tang forces. Yŏn Namgŏn tried to commit suicide, but was seized and treated. This was the end of Goguryeo, and Tang annexed Goguryeo into its territory, with
Xue Rengui being put initially in charge of former Goguryeo territory as
protector general. Furthermore, Emperor Gaozong was much ailing, so Empress Wu took a pacifist policy, and the Tang Empire was diverting resources towards other priorities. This situation favored Silla, because soon Silla would have to forcibly resist the imposition of Chinese rule over the entire peninsula, and there was much resistance to Tang rule (fanned by Silla, which was displeased that Tang did not give the Goguryeo territory to it), and in 669, following Emperor Gaozong's and Empress Wu order, a part of the Goguryeo people were forced to move to the region between the
Yangtze River and the
Huai River, as well as the regions south of the Qin Mountains and west of Chang'an, only leaving old and weak inhabitants in the original land. In 670, Wu's mother, Lady Yang, died and by Emperor Gaozong's and Empress Wu orders, all of the imperial officials and their wives attended her wake and mourned her. Later that year, with the realm suffering from a major drought, Empress Wu offered to be deposed which Emperor Gaozong rejected, so she remained his empress and continued to exercise power by "speaking to him" (like a
co-ruler) or "on his behalf" (de facto
regent). At her request, He further posthumously honored Wu Shiyue (who had previously been posthumously honored as the Duke of Zhou) and Lady Yang by giving them the titles of the Prince and Princess of Taiyuan.
Xianheng era (670–674) In summer 670, the Tibetan Empire captured the 18 prefectures that Tang had established over the
Western Regions (
Xiyu), and Emperor Gaozong, in response, commissioned Xue Rengui, assisted by Ashina Daozhen () and Guo Daifeng (), to attack the
Qinghai Lake area, to try to open a second front against the Tibetan Empire as well as to try to restore the territory previously held by Tuyuhun. However, Guo, who felt himself to be Xue's equal as a general, was displeased at serving as an assistant, and their discord eventually led to a
major defeat at the hands of the Tibetan Empire's prime minister
Gar Trinring Tsendro. For the time being, the Xiyu territory was lost. By 672, Emperor Gaozong gave up the hopes of reestablishing Tuyuhun and moved Murong Nuohebo and his people deep into Tang territory. By 674, Emperor Gaozong and Empress Wu was displeased at King
Munmu of Silla encouragement of
Goguryeo restoration movements who continued to resist Tang rule over the region and he stripped King Munmu of all Tang-bestowed titles, including the title of King of Silla, and arbitrarily conferred them on King Munmu's brother
Kim Immun () instead, commissioning Liu Rengui, assisted by Li Bi (, Li Ji's brother) and the ethnically
Mohe general Li Jinxing (), to escort Kim Immun back to Silla territory. However, King Munmu formally apologized and offered tribute, Emperor Gaozong and Empress Wu drawal and recalled Kim Immun. The
Sassanian prince
Peroz III fled to China during this time around 670. The Chinese Emperor, who allowed Sassanian refugees fleeing from the Arab conquest to settle in China.
Late reign: Problems of succession Shangyuan and Yifeng eras (674–679) In 674, one of Empress Wu claims concerned the title and power of empress; arguing that the Emperor was called Son of Heaven (), his wife should logically be called Empress of Heaven (). As a result, she linked her co-rule with divine right. Around the new year 675, Empress Wu submitted twelve suggestions. One was that the work of Laozi (whose family name was Li and to whom the Tang imperial clan traced its ancestry), Tao Te Ching, should be added to the required reading for imperial university students. Another was that a three-year mourning period should be observed for a mother's death in all cases, not only in those cases when the father was no longer alive. Moreover, degradation and rejection of flattering officials, allowing all officials to speak to the level of chancellors, promotion of competent mid-level officials, military expenses were reduced, taxes cut, salaries of deserving officials raised, retirees given a viable pension, and vast royal lands near the capital turned over to husbandry. Emperor Gaozong praised her for her suggestions and adopted them. In 675,
Li Jinxing reached Silla territory with Mohe forces that submitted to Tang. However, Tang forces were repelled by Silla army at
Maeso fortress. The emperor over the years suffered much more severe headaches from consuming many of the dangerous substances that Empress Wu ordered. Because he could not run the empire, power in the imperial court gradually passed to Empress Wu. Meanwhile, by this time, even more Emperor Gaozong was continuously suffering from a persistent headache, and he considered making Empress Wu
regent, to gain all power. Both Hao Chujun and
Li Yiyan objected strenuously, and Emperor Gaozong did not make her regent, but until the end of his reign, she has decision-making power on most events in the governmental and border matters. Toward the end of Gaozong's life, Wu began engaging a number of mid-level officials who had literary talent, including Yuan Wanqing (),
Liu Yizhi,
Fan Lübing, Miao Chuke (), Zhou Simao (), and Han Chubin (), to write a number of works on her behalf, including the Biographies of Notable Women (), Guidelines for Imperial Subjects ), and New Teachings for Official Staff Members (). Collectively, they became known as the "North Gate Scholars" (), because they served inside the palace, which was to the north of the imperial government buildings, and Empress Wu sought advice from them to divert the powers of the chancellors: They thus act as a secret secretariat, "to process for the empress memorials addressed to the throne, and to make decisions on the policy which were properly the functions of the chancellors". (The modern Chinese historian
Bo Yang suggested that Emperor Gaozong's illnesses may be the result of long-term poisoning by Empress Wu, because of his long and debilitating illness, he often left his responsibilities to Empress Wu, or had to rely on her when himself wanted to address political issues, but did not provide evidence of how the poisoning took place.) Also in 675, Li Hong the Crown Prince died suddenly—with traditional historians largely attributing his death to poisoning by Empress Wu, due to her anger that he tried to curb her power grab and had shown sympathy to his two older sisters born of Consort Xiao—Princesses Yiyang and Gao'an. Emperor Gaozong and Empress Wu, in grief, posthumously honored Li Hong as an emperor, and he created Empress Wu's second son,
Li Xian the Prince of Yong, crown prince. Along with the war with Silla, some resistance of Goguryeo people continued to plague Tang rule there. In 676,
Xue Rengui crossed the
Yellow Sea to fight against Silla. However, Silla navy expelled Tang forces on the coast of western Silla. Emperor Gaozong and Empress Wu order withdrawal of Tang forces from the
Korean Peninsula entirely and moved the
Protectorate General to Pacify the East to Liaodong (, in modern
Liaoyang, Liaoning) and the commandant of Xiongjin (), who governed the former Baekje territory at Sabi, to Geonan (, in modern
Yingkou, Liaoning), allowing Silla eventually to expel Tang out of the
Korean Peninsula and unified the parts of the peninsula south of the
Taedong River. In 677, he bestowed on Goguryeo's former King Bojang, Go Jang, the titles of Prince of
Chaoxian and commandant of Liaodong, giving him the forcibly removed Goguryeo people. He also bestowed on
Buyeo Yung the title of Prince of
Daifang and commandant of Xiongjin—with the intent of letting Go Jang and Buyeo Yung to rebuild Goguryeo and Baekje as loyal vassals to counteract Silla. To accommodate these movements, the Protectorate General was further moved to Xincheng. (Buyeo Yung was not able to make any headway in leading his people back to Baekje territory, while Go Jang tried to break away from Tang rule in alliance with the Mohe; when this was discovered, Emperor Gaozong and Empress Wu recalled him to Chang'an and exiled him to
Qiong Prefecture.) Meanwhile, Tang had to endure multiple attacks from the Tibetan Empire, and in 677, he commissioned Liu Rengui, then a chancellor, to take up defense position at Taohe Base (, in modern
Haidong Prefecture, Qinghai), to prepare a counterattack against the Tibetan Empire. However, Liu's proposals were repeatedly blocked by another chancellor,
Li Jingxuan. In order to retaliate against Li Jingxuan, even though Liu knew that Li Jingxuan was not capable in military matters, he nevertheless recommended that Li Jingxuan take over for himself, and despite Li Jingxuan's attempt to decline, Emperor Gaozong commissioned Li Jingxuan to command the army against the Tibetan Empire. In fall 678, Li Jingxuan's forces
engaged Tibetan forces commanded by Lun Qinling, and was soundly defeated, with Li Jingxuan's assistant Liu Shenli () captured by the Tibetan Empire. Li Jingxuan was only able to escape after being protected by the ethnically
Baekje general
Heichi Changzhi.
Tiaolu, Yonglong, Kaiyao, Yongchun, and Hongdao eras (679–683) Meanwhile, the Western Turkic Khaganate chieftain
Ashina Duzhi had claimed the title of Shixing Khan and was allied with another chieftain, Li Zhefu (), and they pillaged Anxi (i.e.,
Suyab). Emperor Gaozong was ready to commission an army against Ashina Duzhi and Li Zhefu, but the official
Pei Xingjian (), who had previously served as secretary general at Xi Prefecture (, roughly modern
Turfan Prefecture, Xinjiang), opposed—instead proposing that a small detachment be announced to escort the Persian prince
Narsieh back to Persia to contend for regal title. Emperor Gaozong agreed and put Pei in charge of the detachment. When Pei arrived at Xi Prefecture, he, under the guise of a hunting party, summoned a number of tribal chiefs loyal to Tang in the area, and once they arrived, launched a surprise attack on Ashina Duzhi, who, caught by surprise, was forced to surrender; Li Zhefu then surrendered as well. (Narsieh, having been used in this manner, was left in the region to fend for himself.) Meanwhile, though, another trouble was flaring up for Tang. The former Göktürk territory, over which Tang had established 24 prefectures with the tribal chiefs serving as prefects, rebelled, and, under the leadership of Ashide Wenfu () and Ashide Fengzhi (), supported
Ashina Nishoufu as khan. Emperor Gaozong sent Xiao Siye to attack Ashina Nishoufu, but after Xiao achieved a few victories, he became careless, and a counterattack by Ashina Nishoufu crushed him, advancing as far as Ding Prefecture. Ashina Nishoufu also encouraged the
Xi and the
Khitan to attack Ying Prefecture (, roughly modern
Zhaoyang, Liaoning), although those attacks were fought off. Around the new year 680, after Pei returned from the Western Turkic Khaganate front, Emperor Gaozong commissioned him to attack the Göktürks. Pei defeated and captured Ashide Fengzhi, and Ashina Nishoufu's subordinates killed him and surrendered, ending the rebellion. Meanwhile, Li Xian's relationship with Empress Wu was deteriorating, as Li Xian heard rumors that he was not born of Empress Wu but her sister
Lady of Han, and was fearful. Meanwhile, earlier, Ming Chongyan (), a sorcerer trusted by Empress Wu and Emperor Gaozong, had repeatedly stated that he believed Li Xian did not have the abilities to be emperor, that his younger brother
Li Zhe the Prince of Ying had an appearance like Emperor Taizong, and that another younger brother,
Li Dan the Prince of Xiang, had the most honored appearance of all. Knowing that Li Xian was fearful of her, Empress Wu had the North Gate Scholars author teachings on filial piety to give to Li Xian, and also personally rebuked him, further causing him to be alarmed. When Ming was assassinated in 679, Empress Wu suspected Li Xian of carrying out the assassination. She had a report made to Emperor Gaozong that accused Li Xian of assassinating Ming. When the officials
Xue Yuanchao,
Pei Yan, and
Gao Zhizhou were put in charge of investigations, they discovered a number of armors in Li Xian's palace. Empress Wu thus accused Li Xian of treason, and while Emperor Gaozong initially wanted to take no actions against Li Xian, at Empress Wu's insistence he relented. In fall 680, he with her advice reduced Li Xian to commoner rank, and created Li Zhe as the new crown prince. In 681, the Göktürk territory flared up again, as the chieftain
Ashina Fu'nian claimed khan title and allied with Ashide Wenfu to attack Chinese territory. Emperor Gaozong again commissioned Pei to attack Göktürk forces. Pei's assistant Cao Huaishun () was initially defeated by Ashina Fu'nian, but after Pei sent spies to spread rumors, the rumors led to discord between Ashina Fu'nian and Ashide Wenfu. When Pei's forces approached Ashina Fu'nian's position, Ashina Fu'nian arrested Ashide Wenfu and surrendered. (Against Pei's recommendation to spare Ashina Fu'nian, Emperor Gaozong executed him.) In 682, the Western Turkic Khaganate chieftain Ashina Chebo () rebelled against Tang rule, and Emperor Gaozong initially was to commission Pei again, but before the army could depart, Pei died. However, the commandant at Anxi, Wang Fangyi (, Empress Wang's cousin) was able to defeat Ashina Chebo and crush the rebellion. Also in 682, the Göktürk chief
Ashina Gudulu rose, in alliance with Ashide Yuanzhen (), to claim khan title. This, unlike the several earlier rebellions, actually saw the Göktürk khanate being permanently reestablished to Tang's north and persisting for decades, and would plague the last two years of Emperor Gaozong's reign as well as the reigns of his successors. Late in 683, Emperor Gaozong was seriously ill, and he, who was then at Luoyang, and only the Empress Wu were allowed to see her; the chancellors were not, and she attending to his; and at his direction (of course, she was in ruling power for many years), handling the all major affairs of state, and he at her request, summoned Li Zhe, then in charge of Chang'an, to Luoyang to meeted to him, so that at the time of his death he might sit on the throne. In November his illness led him to blindness. Imperial physician Qin Minghe (), hailing from the West/
Daqin (now believed to be from Syria/
Eastern Roman Empire) offered a cure of
acupuncture and
bloodletting, which was applied (and healed the blindness) despite Empress Wu's protests. Of course, he quickly became ill again, and his condition worsened. On 27 December 683, he died. At the time of his death, Empress Wu issued orders forbidding anyone from visiting him, which is why her enemies, and especially later historians, thought that she had killed the emperor. Li Zhe succeeded him (as Emperor Zhongzong), but all actual power still would be in the still hands of Empress Wu, who became
empress dowager; Emperor Gaozong wrote a will that the Crown Prince Li Zhe should immediately seize the throne and that Empress Wu should act as
regent (): ==Hui Islamic legends==