Transition From Sui To Tang - Reintegration Under Tang

Reintegration Under Tang

Around the same time, Li Gui's official An Xinggui (安興貴) captured Li Gui in a coup and surrendered the state to Tang. Tang, however, was facing a threat on a different front, as Liu Wuzhou made a major attack south, taking over much of modern Shanxi, which Tang had controlled, and appearing poised to further attack Tang's capital Chang'an. Around the same time, the lower Yangtze region, which had been in a state of confusion ever since Emperor Yang's death, was coalescing around three different competing figures -- the former Sui official Shen Faxing, who declared himself the Prince of Liang and controlled much of the territory south of the Yangtze; the rebel leader Li Zitong, who controlled Jiangdu and the surrounding regions, declaring himself the Emperor of Wu; and Du Fuwei, who submitted to Tang and was created the Prince of Wu.

In late 619, Tang forces, commanded by Li Shimin, began a counterattack against Liu Wuzhou. By summer 620, Li Shimin had defeated Liu, who abandoned his territory and fled to Eastern Tujue. His Dingyang state was integrated into Tang.

After defeating Dingyang, Li Shimin had his sights set on Zheng. He advanced to the Zheng capital Luoyang and put it under siege. Many Zheng cities surrendered to Tang, forcing Wang to seek aid from Dou Jiande's Xia state. Dou, reasoning that if Tang destroyed Zheng, his own Xia would be cornered, agreed, and he advanced south toward Luoyang, seeking to lift the siege. Around the same time, Du (now using the name Li Fuwei, having been granted the imperial surname of Li by Emperor Gaozu) defeated Li Zitong, who in turn defeated Shen, forcing him to commit suicide. Li Zitong now had Shen's former territory, while Li Zitong's former territory was held by Li Fuwei in Tang's name.

In fall 621, with Dou approaching, Li Shimin advanced east to the important Hulao Pass and held position there. When Dou engaged him, he defeated Dou and captured him. In fear, Wang surrendered. Emperor Gaozu executed Dou while exiling Wang (although Wang was subsequently killed by the Tang general Dugu Xiude (獨孤修德), whose father had been executed by Wang). Wang's Zheng state and Dou's Xia state were annexed by Tang, although former Xia territory soon rose under the leadership of Dou's general Liu Heita, who declared himself the Prince of Handong, and modern Shandong, which had been controlled by the agrarian leader Xu Yuanlang but had successively submitted to Zheng and then to Tang, rose as well under Xu, who declared himself the Prince of Lu.

Also in 621, Emperor Gaozu's nephew Li Xiaogong the Prince of Zhao Commandery attacked Xiao Xian's Liang state, putting the Liang capital Jiangling under siege. Xiao, not realizing that relief forces were approaching, surrendered, and most of his state was annexed by Tang, while some of Xiao's army submitted to Lin Shihong. Around the same time, Li Fuwei defeated Li Zitong, forcing Li Zitong's surrender, and Li Zitong's Wu state was also annexed by Tang.

In spring 622, Li Shimin defeated Liu Heita, forcing Liu to flee to Eastern Tujue, but Liu returned later that year with Eastern Tujue aid, reoccupying the former Xia territory. In winter 622, Li Shimin's older brother Li Jiancheng the Crown Prince defeated Liu again, and in spring 623, Liu, in flight, was betrayed by his official Zhuge Dewei (諸葛德威) and executed by Li Jiancheng. Earlier, Lin had died, and his Chu state dissipated, with the cities gradually submitting to Tang, and soon after Liu's death, Xu, who had repeatedly been defeated by Tang forces, was also killed in flight. By this point, other than Liang Shidu and Gao Kaidao in the extreme north, China was largely reunited, if somewhat nominally, under Tang rule.

In fall 623, however, with Li Fuwei at Chang'an, Li Fuwei's lieutenant Fu Gongshi rebelled at Danyang, declaring himself the Emperor of Song and controlling the territory formerly under Li Fuwei's control. By 624, Li Xiaogong had defeated and killed Fu, reintegrating Song territory into Tang, while Gao, faced with a coup led by his subordinate Zhang Jinshu (張金樹), committed suicide, and his Yan state was also integrated into Tang.

Meanwhile, Liang Shidu, protected by Eastern Tujue aid, was holding up against Tang attacks, and Tang itself was continually harassed by Eastern Tujue raids. After Li Shimin ambushed and killed Li Jiancheng and another brother, Li Yuanji the Prince of Qi in 626 and effectively forced Emperor Gaozu to yield the throne to him (as Emperor Taizong), however, Tang began to turn the situation around. By 628, with Eastern Tujue in internal turmoil due to disagreements between the Jiali Khan Ashina Duobi (Ashina Duojishi's younger brother) and the subordinate Tuli Khan, Ashina Shibobi (阿史那什鉢苾, Ashina Duojishi's son), it was no longer able to protect Liang Shidu, and under Tang siege, Liang Shidu's cousin Liang Luoren (梁洛仁) killed Liang Shidu and surrendered. All of China was now under the rule of Emperor Taizong.