Xiao Yu - During Emperor Taizong's Reign

During Emperor Taizong's Reign

Initially, Xiao Yu remained chancellor, but was soon conflicting with Feng Deyi, who was also chancellor, as Shangshu Pushe (by this point heads of the executive bureau, as Li Shimin previously was head of the executive bureau, but his title Shangshu Ling had thus become a title that his subjects did not dare to take), over Feng's frequent changes of things that they had already agreed on, as well as some other new chancellors that Emperor Taizong had trusted and commissioned, including Fang Xuanling and Gao Shilian. In anger, Xiao submitted a secret petition to Emperor Taizong denouncing Feng, but the petition was inartfully written, offending Emperor Taizong. Meanwhile, an incident occurred where Xiao and Chen Shuda argued before Emperor Taizong, and both were removed from their posts. In summer 627, however, after Feng's death, Emperor Taizong again made Xiao Shangshu Pushe. Later that year, Emperor Taizong discussed attacking Eastern Tujue, which Xiao favored, but Zhangsun Wuji opposed, and therefore Emperor Taizong did not carry out the attack. However, when Emperor Taizong asked Xiao how he felt that the life of the dynasty could be extended, Xiao suggested enfeoffing the imperial princes, and Emperor Taizong agreed and began considering doing so. Around the new year 628, Xiao was again removed from his position, for reasons not stated in history, although in spring 630 he was made a de facto chancellor as imperial censor. Later that year, he accused the general Li Jing, after defeating and capturing Eastern Tujue's Jiali Khan Ashina Duobi, of allowing his soldiers to plunder Tujue's treasures, but Emperor Taizong took no actions against Li Jing, on account of Li Jing's great accomplishment. Meanwhile, Xiao continued to be arrogant and harsh and was again not getting along with the other chancellors. It was said that when Fang, Wei Zheng, and Wen Yanbo had minor faults, Xiao submitted accusations against them which Emperor Taizong did not act on, and Xiao became displeased from it. In fall 630, Emperor Taizong made him an advisor to his son and crown prince Li Chengqian, no longer a chancellor.

In 634, Emperor Taizong commissioned 13 officials to examine the circuits in the empire, to see whether the local officials were capable, to find out whether the people were suffering, to comfort the poor, and to select capable people to serve in civil service. Xiao Yu was made the examiner of Henan Circuit (河南道, roughly modern Henan and Shandong), but on his mission, he overly punished an official who did not listen to the people under him about their suffering by putting him in a block, causing that official's death. Emperor Taizong, however, did not punish him. In 635, Emperor Taizong again made him de facto chancellor, once stating:

After the sixth year of the Wude era, Emperor Gaozu considered deposing the crown prince and making me crown prince, but could not resolve to do so. I was not tolerated by my brothers, and I often feared that instead of being rewarded for my accomplishments, I would be punished. But Xiao Yu was not tempted by material goods or threatened by death, and he was truly a pillar for the empire.

He also wrote a poem to Xiao Yu, including these two lines:

Only in a gust of wind can the strong among the grass be known,

Only in turmoil can the faithful subjects be seen.

He further stated to Xiao, "Your faithfulness and honesty cannot be exceeded even by the holy men of old times. However, your overzealousness to distinguish good and bad sometimes makes you difficult to tolerate."

In 643, Emperor Taizong commissioned 24 portraits at Lingyan Pavilion to commemorate the contributions of the 24 great contributions to Tang Dynasty. Xiao's was one of the portraits. Later that year, Li Chengqian, fearful that Emperor Taizong was considering replacing him with his younger and more favored brother Li Tai the Prince of Wei, plotted with the general Hou Junji to overthrow Emperor Taizong. When the plot was discovered, Emperor Taizong commissioned Xiao, along with Zhangsun, Fang, Li Shiji, and officials from the supreme court, the legislative bureau, and the examination bureau, to investigate. As a result of the investigation, Hou and many other conspirators were ordered to commit suicide or were executed, while Li Chengqian was reduced to commoner rank. Soon thereafter, Emperor Taizong, believing that Li Tai had played a role in Li Chengqian's downfall, created another son, Li Zhi the Prince of Jin, crown prince, instead of Li Tai, and Xiao was made a senior advisor of the new crown prince. Xiao was given a newly created title for a de facto chancellor as well, Tong Zhongshu Menxia Sanpin (同中書門下三品). In 645, when Emperor Taizong commanded a major campaign against Goguryeo, he put Xiao in charge of Luoyang as well as the logistics of shipping supplies to the frontline.

In 646, Xiao was again in discord with the other chancellors, going as far as accusing Fang of factionalism bordering on treason. Emperor Taizong was also displeased with Xiao over his requesting to become a Buddhist monk at one point around this time and then changing his mind. In winter 646, he issued an edict extensively accusing Xiao of being overly obsessed with Buddhism—citing Xiao's ancestor Emperor Wu of Liang and Emperor Wu's son Emperor Jianwen of Liang as examples that Xiao was falling into the traps of. He demoted Xiao to the post of prefect of Shang Prefecture (商州, roughly modern Shangluo, Shaanxi), but also cancelled Xiao's title as Duke of Song. In 647, however, Emperor Taizong recalled Xiao to be an imperial advisor (but not chancellor) and restored his title of Duke of Song.

In 648, while accompanying Emperor Taizong at Yuhua Palace (玉華宮, in modern Tongchuan, Shaanxi), Xiao grew ill and died. The ministry of ceremonies suggested, as a posthumous name, De (德, meaning "virtuous"), while the executive bureau suggested Su (肅, meaning, "solemn"). Emperor Taizong, however, disagreed with both, stating that posthumous names should be particularly reflective of people's characters, and he chose Zhenbian (貞褊, meaning "honest but harsh") instead.