Shimin defeated Dou, capturing him. Despairing, Wang also surrendered, and most of the Zheng territory was seized by the Tang. Xia territory was also seized by Tang, but after Emperor Gaozu executed Dou, Dou's general Liu Heita rose against the Tang and seized most of the former Xia territory, while Xu Yuanlang, a rebel leader who had previously submitted to Zheng, also rose in revolt, occupying the modern Shandong region. Also in 621, Li Xiaogong defeated Xiao Xian the Emperor of Liang, who had controlled the modern Hubei, Hunan, and Guangxi region, forcing Xiao Xian to surrender. On another front, Li Fuwei's lieutenant Fu Gongshi defeated Li Zitong, forcing him to surrender as well. Liang and Wu territory were seized by Tang. Meanwhile, while not as noted as Emperor Gao of Han's killing of Han Xin and Peng Yue, historians have nevertheless noted that some contributors to Emperor Gaozu's establishment of Tang were wrongly killed by him or killed based on fairly little evidence of wrongdoing: Liu Wenjing, in 619, on accusation that he engaged sorcerers. Emperor Gaozu's cousin Dugu Huai'en (), in 620, on accusation of treason. Li Zhongwen () the Duke of Zhenxiang, in 620, on accusation of collaboration with Eastern Tujue. Liu Shirang () the Duke of Yingyang, in 623, on accusation of collaboration with Eastern Tujue. Struggle between sons and the Xuanwu Gate Incident In spring 622, Li Shimin defeated Liu Heita, forcing him to flee to the Eastern Turks, but Liu Heita soon returned with Turkic reinforcements and killed Emperor Gaozu's nephew Li Daoxuan () the Prince of Huaiyang in battle, again seizing former Xia territory, although by this point Li Shimin and Li Yuanji had also defeated Xu Yuanlang and reduced his territory to a few cities. Meanwhile, an intense rivalry had developed between Li Jiancheng and Li Shimin, as while Li Jiancheng had some contributions toward Tang's reunification of China, Li Shimin had been the one defeating and capturing the major rivals Xue Rengao, Liu Wuzhou, Dou Jiande, and Wang Shichong, causing him to possess the greater reputation among the army. Li Yuanji, who was also often relied on by Emperor Gaozu as a general, supported Li Jiancheng in this rivalry, and often pushed Li Jiancheng toward a more hardline position against Li Shimin, wanting to be crown prince when Li Jiancheng would become emperor. Li Jiancheng and Li Yuanji had better relations