Emperor Gaozong of Tang (Li Zhi)

Emperor Gaozong of Tang (628-683), born Li Zhi, ruled from 649 to 683, a reign during which the Tang empire reached its greatest territorial extent. He was the ninth son of Emperor Taizong and the third borne by Empress Zhangsun, and he became heir only after the falls of his elder full brothers: the crown prince Li Chengqian was deposed for conspiracy in 643, and Li Tai was excluded for his part in the rivalry. Taizong reportedly chose Li Zhi in part because his gentler temperament promised safety for his surviving brothers.

The early years of the reign were guided by senior statesmen inherited from Taizong, notably the emperor's uncle Zhangsun Wuji. Gaozong moved against this establishment in the 650s over the question of his consort: in 655 he deposed Empress Wang and elevated Wu Zhao, a former concubine of his father's palace, as empress, over the strenuous objection of the old guard. The ministers who resisted were demoted or destroyed, and Empress Wu's position at court became unassailable.

Militarily the reign was remarkable. Tang forces destroyed the Western Türk khaganate in 657, extending protectorates across the Tarim Basin and into Central Asia. In the east, a Tang-Silla alliance crushed Baekje in 660 and finally brought down Goguryeo in 668, ending a struggle that had defeated both Emperor Yang of Sui and Taizong. Protectorates briefly administered the Korean peninsula and southern Manchuria, though Silla soon pushed Tang administration out of most of Korea, and Tibetan expansion later strained the western holdings.

From around 660 Gaozong suffered recurrent illness, described in the sources as dizziness and impaired sight and sometimes interpreted as a series of strokes. Empress Wu increasingly managed state business, and from 674 the couple were styled the "Two Sages." How far the emperor remained an active partner rather than a figurehead is debated; the traditional histories, written with knowledge of Wu's later usurpation, tend to minimize his agency. Gaozong died at Luoyang in 683 and was buried with Wu at the Qianling mausoleum. He was succeeded nominally by his son Li Xian, Emperor Zhongzong, but real power passed to his widow, who would eventually rule as emperor in her own name.