Zhangsun Wuji

By 623, however, Li Shimin was locked into an intense rivalry with Li Jiancheng, who was supported by another brother, Li Yuanji the Prince of Qi. For the next several years, the rivalry further intensified. By 626, Li Jiancheng and Li Yuanji, apprehensive that Li Shimin might act against them, had falsely accused Li Shimin's staff strategists Fang Xuanling and Du Ruhui and military officer Yuchi Gong and had them removed from Li Shimin's staff. It was said that by that time, of Li Shimin's closest confidants, only Zhangsun remained, and that Zhangsun, his uncle Gao Shilian, Hou Junji, and Yuchi advocated acting first against Li Jiancheng and Li Yuanji. They persuaded Li Shimin to take action. Li Shimin thereafter set up an ambush for Li Jiancheng and Li Yuanji, killing them at Xuanwu Gate, and then effectively forced Emperor Gaozu to create him crown prince. Zhangsun was thereafter made the minister of civil service affairs. Two months later, Emperor Gaozu yielded the throne to Li Shimin, who took the throne as Emperor Taizong.

Later in 643, Li Chengqian the Crown Prince (the oldest son of Emperor Taizong and Empress Zhangsun, who had died in 636), locked into an intense rivalry with his younger brother Li Tai the Prince of Wei, who was also born of Empress Zhangsun and was Emperor Taizong's favorite son, was discovered to have plotted to overthrow Emperor Taizong, along with Hou Junji and Emperor Taizong's sons-in-law Zhao Jie (趙節) and Du He (杜荷, Du Ruhui's son). Emperor Taizong put the investigation in the hands of Zhangsun, Fang Xuanling, Xiao Yu, Li Shiji, and the officials in charge of the supreme court and the legislative and examination bureaus of government, and they determined that, indeed, Li Chengqian had plotted to overthrow Emperor Taizong. Li Chengqian was deposed, while his coconspirators were executed.

A succession question immediately arose. Li Tai was Emperor Taizong's favorite son, and Emperor Taizong almost immediately promised to him that he would be created crown prince, an idea concurred by the chancellors Cen Wenben and Liu Ji. However, Zhangsun did not concur, and instead recommended that Emperor Taizong make his ninth son Li Zhi, also by Empress Zhangsun, crown prince instead; Zhangsun was supported in this suggestion by Chu Suiliang. Further, when Emperor Taizong interrogated Li Chengqian personally, Li Chengqian admitted guilt but blamed Li Tai's machinations for leading him to fear for his own safety and thus plot rebellion. Emperor Taizong thereafter resolved to create Li Zhi crown prince—a decision that he initially secretly informed only Zhangsun, Fang, Li Shiji, and Chu, in addition to Li Zhi himself—and he exiled both Li Chengqian and Li Tai. Subsequently, Zhangsun, along with Fang and Xiao, were made senior advisors to the new crown prince. Thereafter, however, Emperor Taizong began to doubt whether his decision was correct—believing that while Li Zhi was kind, he was also weak in personality, and unsure whether he would be fit to be emperor. He discussed with Zhangsun the possibility of making another son, Li Ke the Prince of Wu (by his concubine Consort Yang, a daughter of Sui's Emperor Yang), who was older than Li Zhi and considered more capable, crown prince instead. Zhangsun strenuously opposed this idea, and Emperor Taizong did not carry it out. Zhangsun further often praised Li Zhi's kindness. Thereafter, a deep enmity developed between Zhangsun and Li Ke.

In 644, when Emperor Taizong, at an imperial gathering, stated to his key officials their strengths and weaknesses, he spoke, with regard to Zhangsun:

Zhangsun Wuji is overly worried about appearance of conflict of interest. He is dexterious and decisive beyond the wisdom of the ancients, but commanding an army in the battlefield is not his strength.

Later in 644, when Emperor Taizong launched a major attack against Goguryeo, he had the generals Li Shiji and Li Daozong lead the forward forces, while commanding the main forces himself, assisted by Zhangsun, Cen, and Yang Shidao. In summer 645, at a major battle against the main Goguryeo forces commanded by the generals Go Yeonsu (高延壽) and Go Hyezin (高惠真) engaged Tang forces, Emperor Taizong had Li Shiji command 15,000 men to serve as decoy, and when Goguryeo forces attacked Li Shiji, Zhangsun Wuji attacked them from behind with 11,000 men, and Li Shiji and Zhangsun, as well as Emperor Taizong himself, defeated Goguryeo forces, forcing their surrender. He then considered directly attacking Goguryeo's capital Pyongyang itself, but Li Shiji believed that if Ansi (安市, in modern Anshan, Liaoning) was not captured first, the general in command of Ansi (a capable general known in Korean popular legends as Yang Manchun, although whether that was his real name is unknown), might attack Tang forces from the rear. Emperor Taizong agreed, and therefore put Ansi under siege again. However, the commander at Ansi was a capable defender, and the resolve of the defenders was strengthened when Li Shiji, in anger, declared that after the fall of the city all residents would be slaughtered. With the Tang forces bogged down in sieging Ansi, a number of officials suggested skipping past Ansi and attacking Ogol (烏骨, in modern Dandong, Liaoning) and then head toward Pyongyang. Zhangsun opposed, believing the strategy to be too risky without first capturing Ansi and Geonan (建安, in modern Yingkou, Liaoning) first. Emperor Taizong agreed and continued sieging Ansi, but still could not capture it. In fall 645, with winter approaching, Emperor Taizong was forced to withdraw. (The Song Dynasty historian Hu Sanxing, the commentator to the Zizhi Tongjian, commented that overcautiousness was what cost Emperor Taizong the victory, indirectly blaming Zhangsun for opposing the strategy to attack Pyongyang directly.) As the army retreated, Zhangsun was responsible for building a temporary bridge over the Liao River to allow the army to cross.

In 647, when Zhangsun's uncle Gao Shilian died, Emperor Taizong, who had just recently himself recovered from an illness, wanted to attend Gao's wake, but Zhangsun lay down in the path of his horse, blocking him, reasoning that as someone who had recently recovered, it was inappropriate for Emperor Taizong to attend the wake. Emperor Taizong, due to Zhangsun's opposition, relented. In summer 647, Emperor Taizong made Zhangsun the commandant at Yang Prefecture (i.e., Jiangdu), but did not actually send him to Yang Prefecture. In fall 647, when a commoner named Duan Zhichong (段志沖) submitted a petition to Emperor Taizong, asking him to yield the throne to Li Zhi, Li Zhi became concerned that Emperor Taizong would suspect that the proposal came from him, and Zhangsun requested that Duan be executed. Emperor Taizong, however, was unfazed, and took no actions against Duan.

In spring 648, Emperor Taizong made Zhangsun the acting head of the legislative bureau—also a chancellor post—and further gave instructions that he also be in charge of the other two main bureaus of government, the executive and the examination bureaus, effectively putting Zhangsun in command of all of the government.

In summer 649, Emperor Taizong was seriously ill, while at the summer palace Cuiwei Palace (翠微宮). He summoned Zhangsun and Chu to his bedside and entrusted Li Zhi to them. He soon died, and by Zhangsun's orders, his death was kept a secret until his casket, accompanied by Li Zhi, was returned to Chang'an. Li Zhi then took the throne (as Emperor Gaozong).

By 654, Emperor Gaozong had become enamored with Consort Wu—whom he had, against Confucian definitions of incest, taken as a concubine even though she had been a concubine of Emperor Taizong's. (Empress Wang, who had been jealous of Emperor Gaozong's then-favorite concubine Consort Xiao, had suggested that he take Consort Wu as a concubine, in order to divide Consort Xiao's favors, but as Emperor Gaozong's favors became exclusively concentrated on Consort Wu, she turned to ally with Consort Xiao against Consort Wu, to no avail.) In 654, after Consort Wu's infant daughter died, Emperor Gaozong began considering deposing Empress Wang and replacing her with Consort Wu. (Historians have suggested that Consort Wu murdered her own daughter in order to frame the Empress, however there is no evidence that the infant was actually murdered, and could have died from natural causes). However, Gaozong feared opposition from the high level officials. He visited Zhangsun's mansion along with Consort Wu, bestowing lavish gifts on Zhangsun and making Zhangsun's three sons mid-level officials, and used the opportunity to bring up the topic of replacing Empress Wang with Consort Wu. Zhangsun pretended not to understand and took no actions to endorse Consort Wu, and persisted in this stand despite later lobbying by both Consort Wu's mother Lady Yang and fellow chancellor Xu Jingzong. However, soon, Xu, Li Yifu (who became chancellor over his overt support for Consort Wu), as well as other key officials Cui Yixuan (崔義玄) and Yuan Gongyu, formed an alliance in support of Consort Wu.

In fall 655, after an imperial gathering, Emperor Gaozong summoned Zhangsun, Li Ji (i.e., Li Shiji—he had dropped the character "Shi" by this point by Emperor Gaozong's orders that naming taboo was to be observed as to the characters Shi and Min, not just the sequence "Shimin" as Emperor Taizong had ordered), Chu, and Yu Zhining to the palace—an order that Chu correctly guessed that was intended to call them into a meeting in which he would try to persuade them to agree with his desire to replace Empress Wang with Consort Wu. Li Ji declined to enter. When Zhangsun, Chu, and Yu attended the meeting, Emperor Gaozong did indeed propose to replace Empress Wang with Consort Wu. Chu objected strenuously, while Zhangsun and Yu did not speak but showed no approval. Later, fellow chancellors Han Yuan and Lai Ji also showed opposition, but when Emperor Gaozong asked Li Ji, Li Ji responded, "This is your family matter, Your Imperial Majesty. Why ask anyone else?" Emperor Gaozong, after demoting Chu to a commandant post at Tan Prefecture (roughly modern Changsha, Hunan), deposed Empress Wang and Consort Xiao to commoner rank and created Consort Wu as empress to replace Empress Wang. (Soon, by Empress Wu's orders, the former Empress Wang and Consort Xiao were tortured and killed.)

By the beginning of 657, the power of Empress Wu and her allies was so great that they began to retaliate hard against the authorities who opposed them. By 659, Empress Wu's position was secure, and she resented how Zhangsun and Yu had shown implicit disapproval of her ascension—and Xu, who had been repeatedly rebuked by Zhangsun over this matter, also resented Zhangsun. Xu thereafter, when investigating a report of factionalism by the low level officials Wei Jifang (韋季方) and Li Chao (李巢), manufactured evidence that Zhangsun had plotted treason with them. Emperor Gaozong wanted to interrogate Zhangsun personally, but at Xu's suggestion—pointing out that Zhangsun had been experienced at quick reactions as demonstrated by his achievements—in summer 659, suddenly stripped Zhangsun's posts and fief, and while he officially gave Zhangsun the title of commandant at Yang Prefecture, he instead exiled Zhangsun to Qian Prefecture (黔州, modern southeastern Chongqing) under house arrest. Zhangsun's sons were also exiled. In fall 659, Emperor Gaozong further reopened the investigations, putting Li Ji, Xu, Xin Maojiang, Ren Yaxiang, and Lu Chengqing in charge of investigating the alleged plot. Xu took this opportunity to send Yuan Gongyu to Qian Prefecture, where Yuan by order of Empress Wu forced Zhangsun to commit suicide. His wealth was confiscated. (As part of the same reprisal transactions, Empress Wang's uncle Liu Shi was also executed in exile. Members of the Zhangsun and Liu households, as well as those of Han's, were forced to hard labor, while several relatives of Zhangsun's were also executed.) Later in Emperor Gaozong's reign, in 674, Emperor Gaozong restored Zhangsun's titles posthumously and allowed Zhangsun's great-grandson Zhangsun Yi (長孫翼) to inherit the title of Duke of Zhao. He also had Zhangsun's casket returned to Chang'an, to be buried near Emperor Taizong's tomb.