Wei Xiaokuan - During Western Wei

During Western Wei

In 538, during a major campaign between Western Wei and Eastern Wei, Wei Xiaokuan accompanied Emperor Wen, and he was made the governor of Hongnong Commandery (弘農, roughly modern Sanmenxia, Henan). He subsequently entered Luoyang (which Western Wei temporarily captured) with Dugu Xin, and for some time tried to defend the city, but eventually they were forced to withdrew from the vicinity of Luoyang. As Wei was then stationed on the borders with Eastern Wei, he became concerned that the Eastern Wei general Niu Daoheng (牛道恆) was capable at drawing the common people of the border region to join Eastern Wei's cause. Wei employed a tactic that he would reuse later—first sending spies to steal samples of Niu's handwriting, and then employing forgers to forge letters purportedly from Niu to Wei offering to defect to Western Wei. He then intentionally allowed spies sent by Niu's superior Duan Chen (段琛) to steal the forgeries, causing Duan to suspect Niu's loyalty and begin to refuse to follow Niu's suggestions. Once Wei was sure of the dissension within the Eastern Wei forces, he made a surprise attack and captured both Duan and Niu, taking the locale for Western Wei.

In 539, Emperor Wen promoted Wei's title from baron to marquess.

In 542, Wei was made the governor of Jin Province (晉州, roughly modern Linfen, Shanxi), and by the recommendation of the prominent general Wang Sizheng (王思政), was given by Yuwen Tai the responsibility of defending the important fort of Yubi (玉壁, in modern Yuncheng, Shanxi), which Wang himself had defended earlier. He managed to pacify the province against raids by the ethnic Xiongnu tribesmen in the area.

In 546, Gao Huan launched a major attack on Western Wei, and as Yubi was an important fort on his path, he put it under siege. He built earthworks to surround the city, hoping to be able to breach Yubi's defenses on top of the walls, but Wei managed to build on top of the towers on top of the walls, always maintaining a higher vantage point than the earthworks and therefore stopping the Eastern Wei attack. Gao then tried digging tunnels below the walls, but Wei was able to anticipate this and dig tunnels himself to connect with Eastern Wei's tunnels, and then setting fires within the tunnels, burning the Eastern Wei soldiers to death. He further set fires to the Eastern Wei army's battering rams, and for every offensive strategy Gao was able to think of, Wei was able to counter it. Gao had his secretary Zu Ting write a letter to Wei, urging him to surrender, but Wei refused. Gao was unable to capture the fort after 60 days of siege, and he grew angry and ill and was forced to withdraw. For Wei's contributions, he was created the Duke of Jianzhong.

In 553, during the reign of Emperor Wen's son Emperor Fei, Wei was made the governor of the capital region, Yong Province (雍州, roughly modern Xi'an, Shaanxi). In 554, Wei participated in the campaign commanded by Yu Jin (于謹) against Liang Dynasty, which eventually captured its capital Jiangling and its emperor Emperor Yuan. (Western Wei eventually put the Liang emperor to death around the new year 555.) After this campaign, Wei's title was changed to Duke of Rang, and as at the time, Yuwen Tai was choosing prominent Han generals to have their names changed to Xianbei names, Wei's name was changed to Yuwen, probably as a sign of respect and endearment on Yuwen Tai's part. In 556, when Yuwen Tai was carrying out a tour of the northern provinces, he returned Wei to the responsibility of defending Yubi.