Emperor Taizong of Tang

Emperor Taizong, born Li Shimin, was the second emperor of the Tang dynasty, ruling China from 626 to 649. A brilliant young general who helped his father seize power from the collapsing Sui, he took the throne by killing two of his brothers, then governed so effectively that his reign, the Zhenguan era, became the model of good rule for later Chinese emperors. Under him the Tang defeated the Eastern Turks and extended its power deep into Central Asia.

Li Shimin was born in 598 at Wugong, near modern Xianyang in Shaanxi, the second son of Li Yuan, Duke of Tang, a senior commander of the Sui dynasty related by marriage to the imperial family. His family belonged to the mixed Chinese and northern aristocracy that had dominated north China for generations, and he grew up skilled in riding and archery.

By the 610s the Sui was falling apart. Emperor Yang's costly wars against the Korean kingdom of Goguryeo and his vast building projects provoked rebellions across the country. In 617 Li Yuan, then based at Taiyuan, rose in revolt; later official histories gave Li Shimin the leading role in persuading his father, an account historians treat with caution, since it was written under Taizong's own supervision. The rebels took the Sui capital, Chang'an, today's Xi'an, late in 617, and in 618 Li Yuan proclaimed himself emperor of the new Tang dynasty, later known as Emperor Gaozu.

Over the next four years Li Shimin, now Prince of Qin, led the campaigns that destroyed the Tang's main rivals. He defeated Xue Rengao in the north-west in 618, and in 621 won his greatest victory at Hulao, defeating the warlord Dou Jiande and forcing the surrender of Wang Shichong at Luoyang in a single campaign. By 624 China was largely reunited under the Tang.

Li Shimin's success made him a dangerous rival to his elder brother, the crown prince Li Jiancheng, who was allied with their younger brother Li Yuanji. Each side built up its own following at court. On 2 July 626, Li Shimin and his supporters ambushed his two brothers at the Xuanwu Gate of the palace in Chang'an and killed them both; their sons were also put to death. Gaozu, faced with his son's control of the capital, named Li Shimin crown prince within days and abdicated in his favour two months later. The new emperor is known by his temple name, Taizong. The killing of his brothers and the pressure on his father remained a stain on his reputation, which the court historians did their best to soften.

Taizong's reign, named Zhenguan, "true view", from 627, is remembered for careful and frugal government. He reduced the number of officials, kept taxes and labour duties moderate, and worked with a group of able ministers, among them Fang Xuanling, Du Ruhui and his brother-in-law Zhangsun Wuji. Most famous was Wei Zheng, who had once advised Li Jiancheng to kill him. Taizong employed him anyway and allowed him to criticise imperial decisions openly, and the relationship between the emperor and his outspoken minister became a classic example of a ruler accepting remonstrance. His wife, Empress Zhangsun, was widely admired for her restraint and good counsel until her death in 636.

The government refined the structure of three central departments and six ministries inherited from the Sui, used the examination system alongside recommendation to recruit officials, and issued a revised legal code, the basis of the Tang Code completed in the 650s, which influenced law across East Asia. Taizong also commissioned official histories of earlier dynasties and a compilation of the leading aristocratic clans that ranked his own family above the old north-eastern elite. He was cautious towards religion, generally favouring Daoism, but he received the Buddhist monk Xuanzang when he returned from India in 645 and supported his translation work, which shaped Chinese Buddhism for centuries.

The Göktürks, the Turkic khaganate of the steppe, had raided Tang territory and in 626 reached the Wei River near Chang'an, forcing the new emperor to buy them off. Taizong rebuilt his cavalry and exploited divisions among the Turks, and in 630 his general Li Jing crushed the Eastern Turks and captured their ruler, Illig Qaghan. Steppe chiefs then hailed Taizong as Tian Kehan, the "Heavenly Khan", recognising him as overlord of the nomads as well as emperor of China. Many Turkish leaders were given commands in the Tang army.

His armies then moved west along the Silk Road. They defeated the Tuyuhun in 635, annexed the oasis kingdom of Gaochang, near Turpan, in 640, and took Karasahr and Kucha in the 640s, pressing back the Western Turks. To the south-west, the rising Tibetan Empire under Songtsen Gampo attacked the Tang frontier in 638, and peace was sealed in 641 when Taizong sent a princess of the imperial clan, Princess Wencheng, to marry the Tibetan king.

Taizong's one major failure came in Korea. After the general Yeon Gaesomun seized power in Goguryeo in 642, and Goguryeo attacked the Tang's ally Silla, Taizong personally led a great invasion in 645. His forces took several fortresses but were held up at the fortress of Ansi, and with winter approaching he withdrew with heavy losses. Further raids followed, but Goguryeo was only conquered under his son in 668.

His later years were troubled by the succession. His eldest son, the crown prince Li Chengqian, plotted against him and was deposed in 643, and another son, Li Tai, who had schemed for the position, was sent away. Taizong chose instead his ninth son, Li Zhi. Taizong died on 10 July 649, possibly hastened by elixirs he had taken, and was buried at Zhaoling, a vast mountain tomb north-west of Chang'an known for its stone reliefs of his war horses.

Li Zhi succeeded him as Emperor Gaozong. One of Taizong's junior consorts, Wu Zhao, later became Gaozong's empress and eventually ruled in her own name as Wu Zetian, the only woman to do so in Chinese history. The Tang empire that Taizong built remained the dominant power in East Asia for more than a century, until the An Lushan Rebellion of 755 shattered it.

Later generations held up the Zhenguan reign as a golden age. A collection of his discussions with his ministers, the Essentials of Government of the Zhenguan Era, was studied by rulers in China, Korea and Japan as a guide to statecraft. Modern historians accept that he was an exceptionally capable ruler, while noting that much of the record was shaped by his own historians, who smoothed over the violence of his rise. The broader story of his dynasty can be followed in the History of China.