Emperor Gaozong of Tang Li Zhi: The Peak of the Prosperous Tang's Territory and the Historical Mirror of "Zizhi Tongjian"

Brief Introduction

Emperor Gaozong of Tang Li Zhi (628–683) was the third emperor of the Tang Dynasty and the ninth son of Emperor Taizong Li Shimin. He reigned for 34 years (649–683), making him the longest-reigning emperor of the Tang Dynasty. Although historically often overshadowed by the narrative of "Empress Wu's dominance," Li Zhi was actually the founder of the Tang Dynasty's peak territorial expansion. His reign inaugurated the "Yonghui Reign" and promulgated the "Yonghui Code," the oldest existing written legal code in China, laying a solid institutional and territorial foundation for the subsequent Kaiyuan Prosperity.

Core Knowledge Points

1. Balancing Consolidation and Expansion: In his early reign, Li Zhi continued the policies of the Zhenguan era, appointing veteran ministers such as Zhangsun Wuji and Chu Suiliang to maintain political stability. At the same time, he did not stop at consolidation; he actively pursued external expansion, demonstrating military boldness that surpassed that of his father.
2. Moment of Territorial Peak: During his reign, the Tang Dynasty defeated the Western Turkic Khaganate and destroyed the kingdoms of Baekje and Goguryeo, establishing the Anxi Four Garrisons. By 669 AD, the Tang territory extended north to Lake Baikal, east to the Korean Peninsula, and west to the Aral Sea, representing one of the largest territorial extents in history.
3. The Rise of Empress Wu's Power: Due to "wind disease" (likely hypertension or cerebral thrombosis), Li Zhi's ability to handle state affairs was affected, and he gradually delegated power to his empress, Wu Zetian. This process is highly controversial in history, but it also reflects the checks and balances and evolution within imperial power, marking a significant turning point in the political structure of the Tang Dynasty.

Connection with "Zizhi Tongjian"

Sima Guang detailed the political changes of the Gaozong era in Volumes 198 to 205 of Zizhi Tongjian, providing a unique perspective that goes beyond official histories.
* Governance Details and Legal System: The book does not simply disparage Li Zhi; instead, it objectively records his improvements to the Imperial Examination System, such as increasing the admission quota for the Jinshi degree, as well as the compilation process of the "Yonghui Code," showcasing his diligent side.
The Beginning and End of Empress Wu's Entry into the Palace: Zizhi Tongjian* provides a detailed description of Wu Meiniang's entry into the palace and how Li Zhi pushed against overwhelming opposition to establish Wu as Empress. Sima Guang uses this to explore the potential dangers of harem interference in politics, yet also acknowledges Li Zhi's willpower in key decisions, revealing the cruelty of court struggles.
* Crisis of Power Transition: The book focuses on the dispute over "Deposing and Establishing the Crown Prince," Li Zhi's hesitation between Li Xian and Li Zhe, and the final process of establishing Li Xian as Crown Prince. This reveals the complexity of imperial succession and the involvement of in-law factions.

In summary, Emperor Gaozong of Tang Li Zhi was not an incompetent ruler, but a complex monarch who maintained the empire at its peak despite health limitations. Zizhi Tongjian provides rich historical support for his image, allowing us to reconstruct a more multi-dimensional portrait of the emperor and understand the political dynamics and historical limitations behind the prosperity of the Tang Dynasty.