Emperor Taizong of Tang (Li Shimin)

Li Shimin, posthumously known as Emperor Taizong of Tang (598-649, r. 626-649), was the second son of the dynastic founder Li Yuan and one of the principal architects of the Tang conquest itself. As a young commander he led campaigns that destroyed rival claimants during the civil wars following the Sui collapse, and his military prestige soon outstripped his formal position as a junior prince behind the crown prince Li Jiancheng.

The rivalry between the brothers ended violently in 626 at the Xuanwu Gate, the northern entrance to the palace in Chang'an, where Li Shimin ambushed and killed Li Jiancheng and another brother, Li Yuanji. Within months he had compelled his father to abdicate in his favor. The episode sat awkwardly with later Confucian moralists, and Taizong is known to have taken an unusual interest in how court historians recorded his accession, a circumstance that complicates evaluation of the sources for his reign.

That reign, designated the Zhenguan era, nonetheless became the standard against which later Chinese emperors were measured. Taizong retained capable ministers such as Fang Xuanling and Du Ruhui, and his tolerance of the blunt remonstrances of Wei Zheng was held up for centuries as the model relationship between ruler and critic. The administration consolidated the equal-field landholding system, refined the legal code, and expanded the examination route into office. Abroad, Tang armies broke the power of the Eastern Türks in 630, after which Inner Asian rulers acknowledged Taizong with the title of Heavenly Khagan; later campaigns extended Tang influence deep into the Tarim Basin, though his expeditions against Goguryeo in the 640s failed to achieve their object.

The succession proved troubled. The original heir, Li Chengqian, was deposed after a conspiracy, and his ambitious brother Li Tai was passed over, leaving the mild ninth son Li Zhi as crown prince. Taizong died in 649 and was buried at the Zhaoling mausoleum. Li Zhi succeeded him as Emperor Gaozong, and a low-ranking concubine of Taizong's later palace, the future Wu Zetian, would in time dominate the dynasty Taizong had stabilized. The idealized image of the Zhenguan reign, codified in works such as the Zhenguan zhengyao, owed something to deliberate curation, but the era's record of internal order and external success was substantially real.