 He therefore sent secret messengers to the general Erzhu Rong, who controlled the region around Bing Province (并州, modern central Shanxi), ordering him to advance on Luoyang to force Empress Dowager Hu to remove Zheng and Xu.After Erzhu advanced to Shangdang (上黨, in modern Changzhi, Shanxi), Emperor Xiaoming suddenly changed his mind and sent messengers to stop him, but the news leaked.Zheng and Xu therefore advised Empress Dowager Hu to have Emperor Xiaoming poisoned.