Wei Zheng - Emperor Gaozu's Reign

Emperor Gaozu's Reign

In spring 619, with Yuan Baozang being attacked by Yuwen Huaji the Emperor of Xu (who had led the coup that killed Emperor Yang in 618), Wei went to Yuan to persuade him to submit to Tang. Yuan did so. Wei apparently subsequently went back to Liyang. In winter 619, when Dou Jiande the Prince of Xia, one of Tang's major rivals, attacked and captured Liyang, Wei was among the people captured by Dou, along with Emperor Gaozu's cousin Li Shentong (李神通) the Prince of Huai'an, Emperor Gaozu's sister Princess Tong'an, and Li Shiji's father Li Gai (李蓋). (Li Shiji was not captured, but several days later felt compelled to surrender to Dou as well, as his father had become a captive.) Dou made Wei his secretary.

In 621, Dou, while trying to aid Wang, under siege at Luoyang by the Tang general Li Shimin the Prince of Qin (Emperor Gaozu's son), was defeated and captured by Li Shimin. The Xia officials initially fled back to the Xia capital Ming Prefecture (洺州, in modern Handan as well) subsequently decided to surrender, and Wei followed Pei Ju back to the Tang capital Chang'an. Emperor Gaozu's oldest son Li Jiancheng the Crown Prince had long heard of Wei's talents, and he invited Wei to serve as his librarian. In 622, with Dou's general Liu Heita having risen against Tang and captured most of former Xia territory, Wei and another staff member, Wang Gui, suggested to Li Jiancheng that due to Li Shimin's accomplishments and fame, he posed a threat to Li Jiancheng, and that Li Jiancheng needed some victories of his own—indicating that he should volunteer to attack Liu. Li Jiancheng agreed, and later in 622 crushed Liu's forces. (Liu was betrayed by his own subordinate Zhuge Dewei (諸葛德威) in early 623 and turned over to Li Jiancheng; Li Jiancheng killed him.) As the brothers' rivalry intensified over the year, Wei repeatedly suggested to Li Jiancheng that he must act first and kill Li Shimin. Li Jiancheng could not resolve to do so.

In 626, however, Li Shimin, believing that Li Jiancheng would kill him, ambushed Li Jiancheng and another brother who supported Li Jiancheng, Li Yuanji the Prince of Qi, at Xuanwu Gate, killing them. He then effectively forced Emperor Gaozu to create him crown prince. He summoned Wei and rebuked him, "Why did you alienate us brothers?" Wei's colleagues were all fearful for him, but Wei, instead of begging for forgiveness, stated boldly, "If the Crown Prince had listened to my words, he would not have suffered this disaster." Li Shimin, who had been impressed with Wei himself, was further impressed by the answer, and he changed his attitude and treated Wei with respect, inviting Wei to serve on his own staff. Subsequently, when he sent Wei on a mission to pacify the eastern prefectures, Wei, believing that no one would believe Li Shimin's words that Li Jiancheng's and Li Yuanji's staff members would be spared if some of them, then under arrest, were not released, ordered them released—an act that Li Shimin was pleased with and impressed by. Later in 626, Emperor Gaozu yielded the throne to Li Shimin (as Emperor Taizong). Wei continued to serve in the imperial administration.