Li Jiancheng - Rivalry With Li Shimin

Rivalry With Li Shimin

Meanwhile, an intense rivalry had developed between Li Jiancheng and Li Shimin, who carried the title of Prince of Qin, as while Li Jiancheng had some contributions toward Tang's reunification of China, a number of the more major contenders, including Xue Rengao the Emperor of Qin, Wang Shichong the Emperor of Zheng, and Dou Jiande the Prince of Xia, were all defeated and/or captured by Li Shimin, causing him to possess the greater reputation among the army. Li Yuanji, who was also often relied on by Emperor Gaozu as a general and had been created the Prince of Qi, 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 with Emperor Gaozu's favored young concubines than Li Shimin did (as their mother Duchess Dou had died before Tang's establishment), and those concubines helped rehabilitate Li Jiancheng's standing before Emperor Gaozu, causing him to no longer consider making Li Shimin crown prince instead, as he considered at one point.

By winter 622, Liu Heita the Prince of Handong, previously a Xia general who rose against Tang after Emperor Gaozu had executed Dou Jiande, posed the only remaining major threat against Tang rule even though he had been defeated by Li Shimin earlier in the year. At the suggestion of his staff members Wang Gui and Wei Zheng, who argued that Li Jiancheng needed some victories himself to establish his reputation, Li Jiancheng volunteered to command the army against Liu Heita. Emperor Gaozu thus sent Li Jiancheng, assisted by Li Yuanji. Around the new year 623, with Liu's forced bogged down while attacking Tang's Wei Prefecture (魏州, in modern Handan, Hebei), Li Jiancheng and Li Yuanji engaged him at Guantao (館陶, in modern Handan as well), crushing him. Liu fled north toward Eastern Tujue, but was ambushed and captured by his own official Zhuge Dewei (諸葛德威), who delivered him to Li Jiancheng. Li Jiancheng executed Liu. China was by this point almost completely unified by Tang.

In 623, when Eastern Tujue made another incursion into Tang territory, Emperor Gaozu again sent Li Jiancheng and Li Shimin to guard against the attack. Meanwhile, at one point, Li Yuanji tried to persuade Li Jiancheng to have Li Shimin assassinated when Li Shimin was visiting Li Yuanji's mansion, but Li Jiancheng, not having the heart to kill a brother, stopped Li Yuanji from doing so.

In 624, Li Jiancheng requisitioned a number of soldiers from the general Li Yi the Prince of Yan, to supplement his guard corps, against Emperor Gaozu's regulations. When this was revealed to Emperor Gaozu, Emperor Gaozu rebuked Li Jiancheng and exiled his guard commander Keda Zhi (可達志). When, subsequently, Li Jiancheng nevertheless requested the commandant at Qing Prefecture (慶州, in modern Qingyang, Gansu), Yang Wen'gan (楊文幹), to conscript troops, presumably to guard against Li Shimin, the officers Erzhu Huan (爾朱煥) and Qiao Gongshan (橋公山) informed Emperor Gaozu that Li Jiancheng was encouraging Yang to start a rebellion so that they could seize power together. Emperor Gaozu, then at Renzhi Palace (仁智宮, in modern Tongchuan, Shaanxi), was incensed, and summoned Li Jiancheng, then at Chang'an, to Renzhi Palace. Li Jiancheng briefly flirted the idea of occupying Chang'an and not accepting the order, but eventually reported to Renzhi Palace to request forgiveness. Emperor Gaozu put him under arrest. When Yang heard this, Yang rebelled, and Emperor Gaozu, after promising Li Shimin that he would be made crown prince, sent Li Shimin to attack Yang. (Under Emperor Gaozu's promise, Li Jiancheng would be removed as crown prince and created the Prince of Shu instead. He would then send Li Jiancheng to the modern Sichuan region.) Once Li Shimin left, however, Li Yuanji, Emperor Gaozu's concubines, and the chancellor Feng Deyi, all spoke on Li Jiancheng's behalf, and Emperor Gaozu changed his mind, released Li Jiancheng, and allowed him to return to Chang'an and remain as crown prince. Instead, Emperor Gaozu only blamed the discord between his sons on Li Jiancheng's staff members Wang Gui and Wei Ting (韋挺), and Li Shimin's staff member Du Yan, exiling them. Yang was subsequently assassinated by his own subordinates.

Later that year, Emperor Gaozu, troubled by repeated Eastern Tujue incursions, seriously considered burning Chang'an to the ground and moving the capital to Fancheng, a suggestion that Li Jiancheng, Li Yuanji, and the chancellor Pei Ji agreed with. Li Shimin opposed, however, and the plan was not carried out. Meanwhile, Li Shimin himself was sending his confidants to Luoyang to build up personal control of the army there. After an incident in which Li Shimin suffered a severe case of food poisoning after feasting at Li Jiancheng's palace -- an event that both Emperor Gaozu and Li Shimin apparently interpreted as an assassination attempt -- Emperor Gaozu considered sending Li Shimin to guard Luoyang to prevent further conflict, but Li Jiancheng and Li Yuanji, after consulting each other, believed that this would only give Li Shimin an opportunity to build up his personal power there, and therefore opposed it. Emperor Gaozu therefore did not carry out the plan.