Empress Wang
In 655, when Emperor Gaozong, whose favors for his wife Empress Wang had waned, believed in the accusations of his favorite concubine Consort Wu (later known as Wu Zetian) that Empress Wang and her mother Lady Liu had used witchcraft and that Empress Wang had killed Consort Wu's daughter, wanted to depose Empress Wang and replace her with Consort Wu. The chancellors Chu, Han Yuan, and Lai Ji all strenuously objected. Zhangsun also showed disapproval by his silent refusal to endorse the acts. Yu was described to be neutral on the matter, while Li Ji stated that it was Emperor Gaozong's own household business. Emperor Gaozong thus became resolved, and he deposed Empress Wang and replaced her with Consort Wu. (Empress Wang was subsequently killed on the new Empress Wu's orders.) In 659, Yu requested to retire from his post, and he was made a senior advisor to the new crown prince—Empress Wu's oldest son Li Hong, but continued to carry the designation of a chancellor "de facto".