The Road to Unification: Tang’s Campaign Against Wang Shichong

In June 620 CE, the Tang Dynasty launched its long-delayed campaign to capture Luoyang, the eastern capital of China. By this time, Wang Shichong, a rival warlord, had expanded his territory significantly, stretching south to Xiangyang, east to Bianzhou (modern Kaifeng) and Qizhou, and bordering another powerful warlord, Dou Jiande, in the northeast.

Wang Shichong’s forces were concentrated in Luoyang and its satellite cities, with key garrisons at strategic points like Xiangyang, Hulao Pass, and Huaizhou (modern Qinyang). His weak point lay in the western mountainous regions of Xiaoshan and Hangu Pass, where the Tang forces, led by the brilliant strategist Li Shimin (later Emperor Taizong), held the advantage.

Li Shimin adopted a methodical approach, isolating Luoyang by cutting off its supply lines. He seized southern routes through Longmen Mountain, northern routes via the Yellow River crossings, and eastern granaries like Luokou. As Tang forces tightened their grip, Wang Shichong’s allies defected, leaving Luoyang increasingly isolated.

The Rise and Fall of Dou Jiande

Wang Shichong’s desperate plea for help reached Dou Jiande, who initially hesitated. Realizing that Tang’s victory over Wang would make him the next target, Dou Jiande reversed course and marched westward. By March 621, his forces reached Hulao Pass, where Li Shimin had entrenched his troops.

Dou Jiande’s advisors proposed bypassing Hulao and striking north into Shanxi, threatening the Tang heartland. But indecision cost him dearly. Li Shimin exploited Dou’s impatience, delaying battle until his troops were exhausted before launching a decisive attack. The Tang victory at Hulao Pass was a turning point—Dou Jiande was captured, and Wang Shichong surrendered soon after.

Consolidating the South: The Fall of Rival Warlords

With the north secured, Tang forces turned south, where three major warlords held power:
– Xiao Xian, a descendant of the Liang Dynasty, ruled from Jiangling.
– Lin Shihong declared himself “Emperor of Chu” in modern Jiangxi.
– Du Fuwei, a Tang ally, controlled the Huai River region.

Tang forces systematically defeated each, beginning with Xiao Xian, then Lin Shihong, and finally crushing a rebellion by Du Fuwei’s general, Fu Gongshi. By 624, the Tang Dynasty had reunified China, establishing an empire that would last 289 years.

The An Lushan Rebellion: A Near-Fatal Blow

The Tang’s golden age was shattered in 755 when An Lushan, a powerful military governor, rebelled. His strategy was masterful:
1. Secure his base in Hebei and Beijing.
2. Protect supply lines while disrupting Tang’s logistics.
3. Capture Luoyang and Chang’an, paralyzing the Tang government.

An Lushan’s early successes were staggering. He took Luoyang and declared himself emperor, but Tang resistance stiffened. Key figures like Zhang Xun (defending Suiyang) and Lu Jiong (holding Nanyang) thwarted his advance into the south. Meanwhile, generals Guo Ziyi and Li Guangbi struck from Shanxi, threatening An’s rear.

### The Critical Mistake: The Fall of Tong Pass

The Tang’s defensive strategy—holding Tong Pass while attacking from the flanks—nearly succeeded. But Chancellor Yang Guozhong, fearing General Geshu Han’s loyalty, pressured Emperor Xuanzong to order a disastrous offensive. Geshu Han’s defeat led to Tong Pass’s fall, forcing the emperor to flee.

An Lushan’s triumph was short-lived. His failure to secure Shanxi left him vulnerable to counterattacks. By 757, he was dead—assassinated by his own son—but the rebellion dragged on until 763, leaving the Tang weakened and decentralized.

Legacy: The Tang’s Strategic Triumphs and Failures

The Tang’s unification showcased the last great triumph of Guanzhong (the Wei River Valley) as a power base. Yet, the dynasty’s overreliance on distant grain supplies from the south made it vulnerable. The An Lushan Rebellion exposed these flaws, leading to the rise of military governors (jiedushi), whose autonomy sowed the seeds of future fragmentation.

The Tang’s story is one of brilliance and fragility—a dynasty that reached unparalleled heights but whose structural weaknesses ultimately led to its decline. Its military strategies, from Li Shimin’s encirclement tactics to the failed defense against An Lushan, remain studied as masterclasses in ancient warfare.