郑注
Soon thereafter, a plot by Emperor Wenzong, Li Xun, and Zheng Zhu to slaughter the powerful eunuchs (later known as the Ganlu Incident) ended in failure — with the eunuchs arresting or slaughtering Li Xun, Zheng Zhu, and many other imperial officials, including Li Xun's fellow chancellors Wang Ya, Jia Su, and Shu Yuanyu — at the eunuchs' prompting, Emperor Wenzong summoned Zheng Tan and his "Pushe" colleague Linghu Chu to the palace to examine a confession by Wang — extracted under torture — that he and the other officials were set to overthrow Emperor Wenzong and replace him with Zheng Zhu. Linghu and Zheng Tan confirmed that the handwriting was Wang's. Subsequently, Emperor Wenzong kept Zheng Tan and Linghu at the Office of the Chancellors to oversee the aftermaths. (Li Xun, Wang, Jia, and Shu were subsequently executed, while Zheng Zhu was killed in an ambush.) Linghu, however, subsequently offended the leading eunuch Qiu Shiliang by drafting an edict that, while condemning Wang and the other chancellors of treason, was in such empty language to imply the lack of believability of the treason allegations, and was not made chancellor. Zheng Tan was subsequently made chancellor "de facto" with the designation "Tong Zhongshu Menxia Pingzhangshi" (), along with Li Shi. Zheng was also created the Duke of Yingyang.