Emperor Gaozong of Tang (21 July 628 – 27 December 683), personal name Li Zhi, was the third emperor of the Chinese Tang dynasty, ruling from 649 to 683; after January 665, he handed power over the empire to his second wife Empress Wu (the future Wu Zetian), and her decrees were carried out with greater force than the decrees of Emperor Gaozong. Emperor Gaozong was the youngest son of Emperor Taizong and Empress Zhangsun; his elder brothers were Li Chengqian and Li Tai.
Emperor Gaozong's reign saw the primacy of Empress Wu, who became the effective power behind the Tang rule.Rothschild, N. Harry (2008). Wu Zhao: China's Only Woman Emperor (1st ed.). Pearson Education. Empress Wu aided Emperor Gaozong in his rule during the later years of his reign after a series of strokes left him incapacitated.Rothschild, N. H. (2005). Wu Zhao's remarkable aviary. Southeast Review of Asian Studies, 27, 73.Rothschild, N. Harry (2008). Wu Zhao: China's Only Woman Emperor (1st ed.). Pearson Education. p. 203. Emperor Gaozong effectively after January 665 delegated all matters of state to Empress Wu; after that the empress acted as the power behind the emperor, "hanging the curtain and listening to politics" (). Gaozong's personal illness, affection and trust of Wu led to her wielding a great deal of power in affairs of state until the end of his reign. From official histories from the later Tang Dynasty to contemporary historians, there exists a lively debate about whether Wu exerted undue influence on Gaozong, or whether they were equal partners in the government. Empress Wu was partially in control of power from November 660 and then totally from January 665 to December 683; there was an equality of power between Gaozong and Wu, which caused them to be called "two saints" (, literally two emperors) both inside and outside.Rothschild, N. Harry (2008). Wu Zhao: China's Only Woman Emperor (1st ed.). Pearson Education. pp. 50. After Emperor Gaozong died in December 683, power fell completely and solely into the hands of Empress Wu, acting as Empress Dowager-regent, "presiding over court and issuing edicts" (); she subsequently became the only empress regnant in Chinese history. After his death, he was interred at the Qian Mausoleum along with Wu Zetian.Rothschild, N. Harry (2008). Wu Zhao: China's Only Woman Emperor (1st ed.). Pearson Education. pp. XV.
During the first part of his reign, Tang territorial gains, which started with his father Emperor Taizong, continued, including the conquest of Baekje, Goguryeo, and the Western Turkic Khaganate, but throughout the 670s, much of those gains were lost to the Tibetan Empire, Silla, Khitans, and Balhae. Further, territory previously conquered that belonged to both the Göktürks and the Western Turkic Khaganate were subjected to repeated rebellions.
Background and life as Prince of Jin Li Zhi was born in 628. He was the ninth son of his father, Emperor Taizong, and the third son of his mother, Emperor Taizong's wife Empress Zhangsun.Rothschild, N. Harry (2008). Wu Zhao: China's Only Woman Emperor (1st ed.). Pearson Education. pp. 27. In 631, he was named the Prince of Jin. In 633, he was made commandant of Bing Prefecture (, roughly modern Taiyuan, Shanxi), but remained at the capital Chang'an rather than reporting to Bing Prefecture. When Empress Zhangsun died in 636, Emperor Taizong was particularly touched by the grief that Li Zhi displayed, and from that point on particularly favored him. Sometime while he was the Prince of Jin, at the recommendation of his grand aunt Princess Tong'an, he married the grandniece of Princess Tong'an's husband Wang Yu () as his wife and princess.
Meanwhile, Li Zhi's two older brothers by Empress Zhangsun, Li Chengqian the Crown Prince and Li Tai the Prince of Wei, were locked in an intense rivalry, as Li Tai was favored by Emperor Taizong for his talent and was trying to displace Li Chengqian. Li Chengqian, in fear, entered into a conspiracy with the general Hou Junji, his uncle Li Yuanchang () the Prince of Han, the imperial guard commander Li Anyan (), and his brothers-in-law Zhao Jie (, who was also his cousin) and Du He () to overthrow Emperor Taizong. The plot was discovered in 643, and Emperor Taizong deposed Li Chengqian. He was initially going to make Li Tai the new crown prince, but later began to believe that Li Tai's machinations were responsible for Li Chengqian's downfall. The powerful chancellor Zhangsun Wuji – Empress Zhangsun's brother—suggested that he make Li Zhi crown prince, a possibility that Li Tai was apprehensive about. Li Tai tried to intimidate Li Zhi, who had been friendly with Li Yuanchang, by pointing out to Li Zhi that Li Yuanchang had been part of the plot and that he should be concerned for himself. When Emperor Taizong noticed Li Zhi worrying about this and was told by Li Zhi of Li Tai's intimidation, Emperor Taizong's mind became set. He exiled Li Tai, and on 30 April 643, he created Li Zhi the new crown prince. He made Zhangsun and two other senior chancellors, Fang Xuanling and Xiao Yu, senior advisors to Li Zhi, and made another chancellor, Li Shiji, the head of Li Zhi's household. At the advice of another key official, Liu Ji, who pointed out that the crown prince needed to have a group of well-learned scholars that he was close to, Emperor Taizong appointed Liu, as well as Cen Wenben, Chu Suiliang, and Ma Zhou, to serve as Li Zhi's friends and advisors.
As Crown Prince Late in 643, Emperor Taizong issued an edict to select beautiful women among good households to serve as Li Zhi's concubines. However, after Li Zhi declined such treatment, Emperor Taizong cancelled the edict. However, during his years as crown prince, he was said to have favored his concubine Pure Consort Xiao, having two daughters (the later Princesses Yiyang and Xuan Cheng) and one son (Li Sujie) with her, much to the chagrin of his wife Crown Princess Wang, who was childless and jealous of Consort Xiao. Three other concubines of his bore his other sons Li Zhong, Li Xiao (), and Li Shangjin ().
Around the same time, however, Emperor Taizong also became concerned that Li Zhi, who was considered kind but weak in character, would not be strong enough to be an emperor, and secretly discussed with Zhangsun Wuji the possibility of making another son by his concubine Consort Yang (daughter of Emperor Yang of Sui), Li Ke the Prince of Wu, crown prince. Zhangsun repeatedly opposed the idea, and Emperor Taizong did not carry this out.() New Book of Tang, vol.80
In 645, when Emperor Taizong launched a campaign against Goguryeo, he took Li Zhi with him to Ding Prefecture (, roughly modern Baoding, Hebei) and then left Li Zhi there to be in charge of logistics, before heading to the front himself. He also left senior officials Gao Shilian, Liu Ji, Ma Zhou, Zhang Xingcheng, and Gao Jifu to assist Li Zhi. After the campaign ended in failure later that year, as Emperor Taizong was leading the army back from the front, Li Zhi went to meet him at Linyu Pass (, now Shanhai Pass). Emperor Taizong suffered an injury during the campaign, and Li Zhi was said to have, as Emperor Taizong's conditions were getting worse, sucked the pus out of his wound, until Emperor Taizong recovered somewhat. In 646, with Emperor Taizong still recovering, he transferred some of the imperial authorities to Li Zhi. Li Zhi stayed at the imperial palace and attended to Emperor Taizong in his illness. That year, when Emperor Taizong was due to visit Ling Prefecture (, roughly modern Yinchuan, Ningxia) to meet with a number of tribal chiefs who were formerly vassals of Xueyantuo—which had collapsed under Tang and Huige attacks earlier that year—he was set to take Li Zhi with him, but at Zhang's suggestion left Li Zhi in charge at Chang'an instead, to allow Li Zhi to become more familiar with the important affairs of state in his absence. After Emperor Taizong returned from Ling Prefecture, he retained for himself the authorities over imperial worship, state guests, military, the commissioning of officers of higher than the fifth rank, and executions, and transferred all other authorities to Li Zhi.
In 647, a commoner named Duan Zhichong () submitted a petition to Emperor Taizong, asking him to pass the throne to Li Zhi. Li Zhi, concerned that Emperor Taizong might be offended, was worried and grieving, and Zhangsun suggested that Duan be executed. Emperor Taizong did not take offense and did not punish Duan or Li Zhi. Meanwhile, Li Zhi began to build a Buddhist temple named Daci'en Temple () in commemoration of his mother Empress Zhangsun, and the temple was completed in 648.
In 649, while at the summer palace Cuiwei Palace (, in the Qin Mountains), Emperor Taizong was gravely ill, and he, while impressed with Li Shiji's abilities, was concerned that Li Shiji was too able and would not submit to Li Zhi. He stated to Li Zhi:(上谓太子曰：“李世𪟝才智有馀，然汝与之无恩，恐不能怀服。我今黜之，若其即行，俟我死，汝于后用为仆射，亲任之；若徘徊顾望，当杀之耳。”) Zizhi Tongjian, vol.199
He then demoted Li Shiji to the post of the commandant of Die Prefecture (, roughly modern Gannan Tibetan Autonomous Prefecture, Gansu). Li Shiji, realizing what was happening, after receiving the order, departed without hesitation.
As Emperor Taizong's illness was getting more serious, Li Zhi continuously attended to him and wept constantly, often going without food, which touched Emperor Taizong greatly. Emperor Taizong entrusted Li Zhi to Zhangsun and Chu Suiliang, and then died on 10 July 649.According to Taizong's and Gaozong's biographies in the Old Book of Tang, Taizong died on the jisi day in the 5th month of the 23rd year of the Zhenguan era of his reign. This date corresponds to 10 Jul 649 on the Gregorian calendar. Old Book of Tang, vol.4. Initially, Li Zhi was so mournful that he could not carry out any actions other than holding onto the necks of Zhangsun and Chu. Zhangsun, while mourning himself, reminded Li Zhi that he was now in charge of the empire and must act accordingly. Zhangsun also ordered that Emperor Taizong's death not be announced for the time being, and then, the next day, accompanied Li Zhi back to Chang'an. Zhangsun issued several edicts in Emperor Taizong's name—including making Yu Zhining, Zhang, and Gao Jifu chancellors. Two days later, Emperor Taizong's death was officially announced. On 15 July,According to Gaozong's biography in the Old Book of Tang, he ascended the throne on the jiaxu day in the 6th month of the 23rd year of the Zhenguan era of Taizong's reign. This date corresponds to 15 Jul 649 on the Gregorian calendar. Old Book of Tang, vol.4.， Li Zhi took the throne (as Emperor Gaozong).
Reign as Emperor
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 (649-659) Chu Suiliang (649-655) 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.)